This has been an intermittent problem with this machine since I got it, and it is driving me nuts. I started off with a clean install of Windows 7 Ultimate 64x, and soon after it began: the screen toggling, ON ITS OWN, between normal mode and full mode, sometimes so quickly I thought I had to be high on something... It was impossible to read anything, type, hit the right item with the mouse pointer, etc. It started more often with web browsers (no surprise, since browsers are on my screen a lot of the time), IE, FF, Chrome, but also happened with Windows Explorer screens, Control Panel, MS Word, etc. I thought there was a correlation between the problem and Firefox updates, but was never able to confirm that. Video card drivers (mine is an HD Radeon 6670) were always current. I went online to figure out how to fix it, and one piece of advice I got was to uninstall IE, which I did. That didn't help. Then I found a post mentioning the edge of the browser window shouldn't "touch" the top edge of the screen. I resized my browser windows and that seemed to fix it. Until today...
Again my screen is doing the normal mode - full mode demented toggling. I have noticed that at times there seems to be a relation between typing and toggling (it makes for a VERY frustrating experience). Searching your forum, I found a post mentioning changing from Aero to basic desktop themes, and I have done that. Initially nothing changed. So I set up a little camera in front of the screen, hoping to record a little video that would illustrate how crazy this is. OF COURSE, from the moment the camera was up, the screen has been rock-solid...
I am now wondering if the Aero - basic screen change has actually fixed it! But not really counting on that, I turn to Edugeek forum for some enlightened advice. Thanks!