Photoshop CS4 locks up when ruler tool is used

I have a 24" IMac with system 10.5.6, 2.33 GHz core 2 duo processor 4 Gig L2 Cache 3 Gig memory.
When attempting to use the measure tool photoshop locks up and the image that I am working on turns to wide bands of noise. I have to use force quit to get out.

I have no problem using the ruler tool with Photoshop CS3, however Photoshop CS4 extended locks up every time.
I tried repairing permissions -- no luck.

Any Ideas??

Dave

Have you tried trashing the Photoshop preferences?

This Adobe tech note tells you how to do that automatically or manually.

<http://www.adobe.com/go/kb405012>

" To recreate the preferences files for Photoshop, start the application while holding down Ctrl+Alt+Shift (Windows) or Command+Option+Shift (Mac OS). Then, click Yes to the message, "Delete the Adobe Photoshop Settings file?" "

I just tried that and got the same result after trashing the Photoshop preferences.

Dave

Try turning OFF OpenGL and relaunch the application. This will tell you if it's a video driver or video card issue.

Turned off OpenGL and Photoshop works!!

Thanks Ramón

Dave