When I open up CERTAIN apps on an Acer Aspire X1200 the size constantly fluctuates between full screen and smaller screen multiple times per second. When they are fluctuating you cannot click on any any part of their screens to do anything with them, the only way to stop it is by hitting ALT(this works some of the time). Otherwise they have to be closed and then open numerous times until it just stops behaving this way and opens normally. This happens 90% time the computer is restarted, the other 10% a couple of the effected apps work fine while the majority will have the fluctuating issue. I've done a complete system restore and had everything set to the factory default to no avail. I've tried different settings with the monitor-nothing. The applications effected are all window applications(pictures, explorer, control panel, etc.) as well as the apps that came preloaded from Acer, the only manually added affected app is Firefox. Not affected are the apps I added; Ad-aware, Avast and Lexmark. The power supply has been replaced by Acer, other than that nothing else has been done internally. This issue happened prior to the computer ever being logged on the internet. I have been trying to get in touch w/ Acer's level 2 techs, but to no avail. Any suggestions?

Acer Aspire X1200
Amd Sempron Dual Core Processor 2300 2.20GHz
3.0 GB RAM
32-bit
Windows Vista
Only computer on home network
No viruses or malware detected
Acer X203H monitor

Sorry if I posted this in the wrong forum:(