External Display Issues

[GForce360]

I have a Macbook Pro (Penryn 2.5 ghz 4,1) running 10.6.6

I have a VGA TV that I connect it to and use as an external display, through the apple DVI to S-video/RCA cord. This has worked fine for 2 years. Recently, I was in an application (I started it with an accidental click) that changed the resolution from 800x600 into something higher, upon exiting, the resolution did not return to normal, instead the screen (external) is gray and flickering horizontal bars up and down across the screen (as if the refresh rate was off set wrong).

Having the lid open makes the computer display as before on the external display, the monitor displays fine no matter what resolution it is at, I can't even see my display preferences when the lid is closed, it could be something as simple as changing it manually.

I have tried resetting the PRAM, to no avail. I don't have any appropriate Time Machine backups to use.

Any help you can offer would be fantastic, thanks.

 

[ElDiabloConCaca]

Sounds like you may have enabled "Display Mirroring," which forces each display of your computer to display the same image with the same resolution. Since your TV supports a different native resolution than your MacBook, this may be causing the problem.

With the laptop lid open, head over to the "System Preferences," then "Displays," then check to see if "Mirror Displays" (or some similarly-worded option) is enabled. If so, disable it, then select the correct resolution for your external display.

Let us know if that does or does not work for you.