Strange lack of video display

My iMac has recently started behaving very oddly for no apparent reason (no recent software installs, no recent updates etc).

When it boots up, everything loads but there is no video display -- only a black screen with the backlight behind it. It still logs on and OS X loads up, because I can use screen-sharing from my MacBook Pro to see the normal desktop and run all programs. At some random moment, the display suddenly kicks in. Weird.

The console logs are filled with two repeating messages:

".com.apple.coreservicesd[59] NOTE: Using non-mach-based version of client -> server communication, via direct function calls."

".com.apple.systempreferences[219] objc[219]: Class O3Panel is implemented in both /System/Library/MonitorPanels/AppleDisplay.monitorPanels/Contents/Resources/Authorization.monitorPanel/Contents/MacOS/Authorization and /System/Library/MonitorPanels/AppleDisplay.monitorPanels/Contents/Resources/TVOptions.monitorPanel/Contents/MacOS/TVOptions. Using implementation from /System/Library/MonitorPanels/AppleDisplay.monitorPanels/Contents/Resources/TVOptions.monitorPanel/Contents/MacOS/TVOptions."

or some similar variation. The first message seems to have something to do with networking, as it appears every 15 minutes or if I access anything over my network. A Google search has not turned up anything useful.

Any ideas anyone? Thanks.

you don't say how old your iMac is. Maybe if you are within warranty you should contact Apple

Which OS version are you running ? There was a Graphics Firmware update not too long ago but it could be installed already on your system depending on the OS version you are using.

Exact version number please.

My iMac is 14 months old; I did purchase AppleCare when I bought the machine, and this may be covered under warranty, but I haven't taken it in for service because I can't afford to be without it at the moment (only just got the brand new MBP back from service after the motherboard died only 3 weeks after purchase) and I thought it might be a simple issue I could fix.

I'm running 10.5.2. I installed the graphics update via Software Update soon after upgrading to 10.5.1, although I hadn't been having any graphics trouble at that stage. But that was at least a couple of months ago, and this issue has only just reared its ugly head.

Hmm. The first message could be an app phoning home but I'm not really sure either.

What I would do is create a new user account, use it for a while and check to see if I get the same messages.

I'm with MHC on this one. My first guess would be that your user account has gotten messed up somehow. The first and best test is to see how it behaves under a new user account. If your account has been messed up, this "clean slate test" will show that up nicely. Let us know how it goes.

I'll give that a go -- but I don't see how that will fix the video problem. Probably two unrelated issues ... looks like the iMac might be in for a trip to the store ...

OK, this just got clearer & more complicated all at once.

The video issue persists, but the "Class O3Panel" messages have all disappeared from the Console. No idea what that means.

Tried a new user account, and no error messages at all. Went back to my account and, guess what ... no error messages at all. Then I noticed that Bluetooth is 'Not Available' with the menu bar icon grayed out with a squiggly line through it. This is the case in both accounts. So, could this be a Bluetooth problem?

I have been having an issue with Bluetooth for some time where, on random occasions when I boot up, Bluetooth is unavailable. Rebooting usually fixes this. Googled the problem, saw others had been having the same issue but no one had found a solution. Didn't notice the Console messages at that stage.

So, the question is -- is this a driver issue or a hardware issue? Does anyone know what a "non-mach-based version of client -> server communication, via direct function calls" actually is?

And, going back to my original post, why is my video being so weird???

Thanks again.

The plot thickens

Sorry to re-post to my own thread, but maybe someone can shed light on all of this.

The video display issue has seemingly vanished after a power interruption and subsequent reboot. Is it possible that this has reset the PMU, and the original problem was caused by the video card not correctly being activated?

However, the same reboot now has Bluetooth working again, and my Console filled with the 'non-mach-based version' error messages. I've attached a screenshot of the Console as an example.

What I don't understand is, why do I get these error messages when Bluetooth is working, but no error messages when Bluetooth is not working? The only thing I can think of is that there is some error in the Bluetooth component of OS X that sometimes causes it to work with lots of errors but other times to not work at all.

If anyone has any ideas about how to actually FIX this, I'd be really grateful!