HUGE PROBLEM! Undo doesnt work. CS3 Extended

Ok this is an odd problem that I have not been able find a resolution to, and I've spent a few days searching. Up untill recently, my CS3 extended worked just fine. But suddenly the Undo/Step backward stopped working normally. What happens is when I do step backwards, it looks as though nothing has happened. Whatever it is I wanted undone was still on the screen as though I hadnt pressed undo at all. Well, the second I click down on the image and start drawing, whatever it is I undid disapears finally...

I dont know if I'm explaining this very well, but I hope someone out there knows what I'm talking about. I've tried uninstalling/reinstalling, deleting prefrences, going into the documents & settings/user/application dada/adobe/blablabla and deleting the prefrences there, and nothing has worked.

PLEASE! Someone tell me whats going on!

reset your preferences per the faq.

Read the post again, please. I tried that. And I highly doubt its my laptop, as I have 512mb gfx card(2x256 in sli), 4 gigs ram, and an AMD 64bit 2.4ghz processor.

You don't mention the OS.

CS3 is only certified for 32-bit editions.

It has been working flawlessly as of just a day or two ago, though.

Could it have been a button I pressed? Is that part of the history brush? Is there actually a setting that I might have accidentally enabled?

Could it be a driver issue. If it only appears to change on screen after you do something else, perhaps a redraw is not happening. Did you change anything to do with the screen (video drivers, or perhaps install a new piece of software)?

Nope, I sure didnt. Is CS3 using DirectX, or OpenGL, or another form of drawing? If so, is there a way to change which it is using?