Desktop ikons vanish when clicked on

I have an iMac 2.16 GHz Intel Core 2 Duo running 10.6.8 and it has developed a problem where, if I click on any ikon or folder on the desktop, everything disappears for approximately 3 seconds and nothing opens. If I repeat the process several times, often (but not always) it will eventually open on around the 30th attempt.

Does anyone have any idea what might be causing this? I can't seem to find any reference to anyone else having this problem, which seems odd.

The Console message I get when it happens is:

14/02/2014 11:40:55 com.apple.Finder[195] Finder(195,0x101e84cc0) malloc: *** error for object 0x1120a0408: incorrect checksum for freed object - object was probably modified after being freed.
14/02/2014 11:40:55 com.apple.Finder[195] *** set a breakpoint in malloc_error_break to debug
14/02/2014 11:40:58 com.apple.launchd.peruser.501[94] (com.apple.Finder[195]) Job appears to have crashed: Abort trap
14/02/2014 11:41:02 [0x0-0x17017].org.mozilla.firefox[162] console.error: unblocker:
14/02/2014 11:41:02 [0x0-0x17017].org.mozilla.firefox[162] Message: TypeError: response.json.data is undefined
14/02/2014 11:41:02 [0x0-0x17017].org.mozilla.firefox[162] Stack:
14/02/2014 11:41:02 [0x0-0x17017].org.mozilla.firefox[162] loadConfig/<.onComplete@resource://gre/modules/XPIProvider.jsm -> jar:file:///Users/alan/Library/Application%20Support/Firefox/Profiles/u649rze2.default-1376161058062/extensions/%7B14816161-719a-4683-b6a6-aad2304e431f%7D.xpi!/bootstrap.js -> resource://gre/modules/commonjs/toolkit/loader.js -> resource://youtubeunblocker-at-unblocker-dot-yt/unblocker/lib/main.js:418
14/02/2014 11:41:02 [0x0-0x17017].org.mozilla.firefox[162] emit@resource://gre/modules/XPIProvider.jsm -> jar:file:///Users/alan/Library/Application%20Support/Firefox/Profiles/u649rze2.default-1376161058062/extensions/%7B14816161-719a-4683-b6a6-aad2304e431f%7D.xpi!/bootstrap.js -> resource://gre/modules/commonjs/toolkit/loader.js -> resource://gre/modules/commonjs/sdk/event/core.js:94
14/02/2014 11:41:02 [0x0-0x17017].org.mozilla.firefox[162] onreadystatechange@resource://gre/modules/XPIProvider.jsm -> jar:file:///Users/alan/Library/Application%20Support/Firefox/Profiles/u649rze2.default-1376161058062/extensions/%7B14816161-719a-4683-b6a6-aad2304e431f%7D.xpi!/bootstrap.js -> resource://gre/modules/commonjs/toolkit/loader.js -> resource://gre/modules/commonjs/sdk/request.js:98
14/02/2014 11:41:03 ReportCrash[887] Saved crash report for Finder[195] version 10.6.8 (10.6.8) to /Users/alan/Library/Logs/DiagnosticReports/Finder_2014-02-14-114103_Alan-Holmess-iMac.crash
14/02/2014 11:41:03 ReportCrash[887] Failed to write crash history. Error: 1 Operation not permitted
14/02/2014 11:41:10 Finder[888] CFPropertyListCreateFromXMLData(): Old-style plist parser: missing semicolon in dictionary.

Have you tried:
Restart
Repair Drive (not permissions) in Disk Utility
Combo update

Except for the first three, all the lines in your Console report are for Firefox. Got anything else?
Look in Diagnostics for the Finder crash log.

Well, this is what I get when no applications are open:

14/02/2014 16:23:38 com.apple.launchd.peruser.501[87] (com.apple.Finder[121]) Job appears to have crashed: Segmentation fault
14/02/2014 16:23:38 ReportCrash[108] Saved crash report for Finder[121] version 10.6.8 (10.6.8) to /Users/alan/Library/Logs/DiagnosticReports/Finder_2014-02-14-162338_Alan-Holmess-iMac.crash
14/02/2014 16:23:38 ReportCrash[108] Failed to write crash history. Error: 1 Operation not permitted
14/02/2014 16:23:43 Finder[137] CFPropertyListCreateFromXMLData(): Old-style plist parser: missing semicolon in dictionary.

How do I get to diagnostics, considering that nothing that isn't in my dock seems to be accessible?

I can almost guarantee you that over the years...3rd party software has been installed on this computer...and that 3rd party software is conflicting with the Mac OS.

The very first thing I would do is...disable any apps that "auto-start"/"auto-launch" when the computer is booted.

- Nick

Sounds feasible, but how do I do that?

oymyakon said:

Sounds feasible, but how do I do that?

Click to expand...

Take a look here:

- Hard Drive > System Folder > Library Folder > Startup Items Folder

Another place to look:

Apple Menu > System Preferences > Users & Groups > Login Items Tab...then see what's there.

- Nick

p.s. Another way to easily test things is to have a fresh copy of the OS installed on an external HD...then boot the computer from it.

Or in addition to the helpful hints from Nick, start your iMac in safe mode. That kills all third party drivers and startup programs. You can then see if the same happens when in safe mode. Hold down your shift key and reboot to get into safe mode.

Does anyone think it could be a corrupt Desktop plist file? ... or Finder?

Nothing at all in the Startup items folder, and yes, still does the same when booted in safe mode.

oymyakon said:

Nothing at all in the Startup items folder, and yes, still does the same when booted in safe mode.

Click to expand...

It's almost definitely a software issue. And to confirm it...booting from an external HD with a fresh OS install is a good way of testing/confirming.

Some additional suggestions:

- You could repair permissions via Disk Utility.
- Download the free maintenance program called "Onyx"...and run the Automated functions.
- As a last resort...you could reinstall the OS (in case something has gotten corrupted).

* Nick

OK... I've tried all these suggestions to no avail. I haven't tried booting from an external drive as I don't have one which the OS is able to be installed on. However, I have tried reinstalling the OS on the iMac and that doesn't make any difference. Have also run Onyx and Disc Utility but the problem remains. I've also trashed the preference files.

I guess the next step is a clean install, if that's not what you did. I assume you didn't from your statement about not having an external to use for booting from, but if you can back everything up or clone your internal drive, then a clean install would not be as big of a pain in the neck.

Anyone agree with that? Other suggestions?

I actually have tried that - not today, but the problem's been around a few months - I did it a while back and it didn't work either... it was fine for a couple of days but then returned.

Any idea what this line from Console means and might it be a clue?

15/02/2014 13:24:15 Finder[330] CFPropertyListCreateFromXMLData(): Old-style plist parser: missing semicolon in dictionary.

oymyakon said:

I actually have tried that - not today, but the problem's been around a few months - I did it a while back and it didn't work either... it was fine for a couple of days but then returned.

Click to expand...

That would definitely indicate to me it's some piece of software installed that is not playing nice with Finder.

Does booting into Safe Mode exhibit the same symptom? - edit sorry - you already did that - just read the entire thread....
Or the guest account?
Or have you tried creating a new user account to see if it does it there?

edited:
Next, think I'd run memtest or switch out the memory just to see what happens.

Safe mode exhibits same symptoms, new user / guest account doesn't seem to.

Is there any way of determining which piece of software is the problem short of deleting them one by one?

That's even more strange that safe mode does and a new user account doesn't.

Aside from testing the memory - need to scratch my head for awhile.

As for what apps to look at... would start off looking at:
antivirus software or parental control apps
any and all maintenance apps
any file management apps
all of the above would likely need to be removed by using the proper uninstaller, not just dragging them to the trash

If you do a permissions repair, does that fix it for any period of time - try it in Safe Mode.

Are there any other issues - slow drive - takes a long time to boot, over a minute...

oymyakon said:

OK... I've tried all these suggestions to no avail. I haven't tried booting from an external drive as I don't have one which the OS is able to be installed on. However, I have tried reinstalling the OS on the iMac and that doesn't make any difference. Have also run Onyx and Disc Utility but the problem remains. I've also trashed the preference files.

Click to expand...

If nothing has helped...and you haven't tried the fresh OS install on an external drive...then you have to try that.

Way back at the beginning of this thread I mentioned that some sort of software was installed at some point that is conflicting or has modified an OS file(s) in some way. Unless you can identify this software, undo what it did, or uninstall it...the problem will not go away.

This is the problem with downloading & installing too many 3rd party apps...especially apps that customize the interface or appearance of things in some way...you end up with problems like this.

Given the number of things you have tried...I'm thinking you have two options:

- A fresh OS install on an external drive (JUST a fresh OS install on the drive)...and then boot the computer from it. Then verify the problem is gone.
- A more radical (and in the end probably what needs to be done anyway)...COMPLETELY erasing the internal HD (nothing on the drive). Then reinstalling the OS...verifying that the problem is gone. Then reinstall your apps.

Unless you can identify the app or apps that is causing the problem (and uninstalling it/them)...the more radical approach mentioned above is what may need to be done (or continue to live with the problem).

- Nick

oymyakon said:

Safe mode exhibits same symptoms, new user / guest account doesn't seem to.

Is there any way of determining which piece of software is the problem short of deleting them one by one?

Click to expand...

Needle in a haystack, IMO. Probably easier to create a new account and move your stuff to it.