iMac Does strange things (recently)

I purchased my iMac when it had Leopard installed. Through the years, I've done all the software upgrades. I am now using Yosemite 10.10. Last night I shut down the system. Problem 1: This morning when I tried to startup the computer, I clicked on my avatar, (my wife also has her avatar and then the guest) only to have a password automatically entered...just not my password. I would not let me delete it so I rebooted. It also gives an annoying noise like a rapid fire machine gun. I shut off the speakers so I don't have to listen to that. Same thing happened every time I rebooted. I then clicked on sleep on the startup screen and it started as it should. Problem 2: When I log out, I can see a blurred image of my wife's background screen even though she is not logged in. Any ideas? I do have Time Machine running and have erased and reloaded from TM with success for a limited time. We are not gamers nor are we running a lot of different programs, just mainly reading the news and running a few Numbers spreadsheets...None of this happened when running Snow Leopard or Mavericks...any thoughts as to what may be happening? Thanks

It sounds like your iMac is entering into old age. Having purchased it with Leopard installed means that you've had it since 2008-2009. Since you now have Yosemite installed, it might be a good idea to verify the hard drive first. Reboot the machine to recovery - hold down the command and r keys and restart. Once in recovery, select utilities, Disk Utility, and verify the hard drive. Let's see what it says.

The blurred image in the background when you log out could be a graphics problem but could also be the sign of an aging LCD. When you post back, give us the exact model and year of your iMac which will help us to answer your questions.

Not the news I was hoping to hear...Will reply later this evening with spec's when I get off work. Thanks again

If it came with OS X.5 Leopard, it is a 2007 model. When booting next time go into Recovery and run Repair Disk from Disk Utilities. Command + R after the chime will get you into Recovery but at eight years old time is marching on.

Thanks for the help...I think I have the Mac that keeps giving. This afternoon when I got in from work, my wife tells me the "M" key is not working any more on my wired keyboard. A week ago, the Caps lock on my wireless keyboard quit so that is what prompted me to use my spare wired KB.

Here's what I've got:
IMac 20" Early 2008.

When I ran verify disk it comes back with,"The volume Macintosh HD appears to be OK".

For grins, I run verify disk permissions. All appeared to be ok until I got this message: Warning SUID File "System/Library/CoreServices/RemoteManagement/ARDAAgent.App/Contents/MacOS/ARDAgent" has been modified and will not be repaired.

Then I did a repair disk permissions. After a reboot, it started as if nothing was wrong but I still have the background issue happening.

In your opinions, wait until it dumps completely or go get a new unit so I can still transfer files? What is the best way to get files from one mac to another...just in case.

Thanks again for all the help and advice.

Thanks for posting back and doing the disk check. With a machine that old, the best thing you can do is to keep up with your backups. Make sure that you especially backup things that are not easily replaceable such as family photos, favorite music, etc. Sometimes even when the hard drive checks OK, it could be intermittent. The graphics processor could also be acting up. Just keep watch on the machine and it's best to put the machine to sleep rather than turn it off. Turning a machine on and off actually puts more wear and tear on components rather than putting it into low power mode. (sleep) If you need any more assistance, just post back to this same thread.

Since I'm no expert I'll ask the obvious...Is my time machine a good backup or would you suggest a flash drive to backup photos? and thanks again for he words of wisdom...even though they are expensive words..

Having had the experience of a crashed hard drive - please backup to an external drive. I still have my crashed disk in a box waiting for the cost of a clean room recovery (now at $3K) to go down. I cannot get at some late addition photos of a Panama Canal cruise because I did not back up to a DVD disk in time.

I am backing up to an external drive so I should be ok...but just in case, will do the flash drive as well. Thanks again to all who offered words of wisdom...Greatly appreciated!