i hate adobe... by the time i update it my hard drive needs to be reformatted.... i dont like to turn off my computer, it leaves me a sense of emptiness when that screen is black
try letting the updates go, but i doubt thats it.
clean out your temp folder and all other "Temporary Internet Files" and stuff like that in the user data, there could be something phishy goin on [pun intended]
how long have you had the PC? what brand (made by you?)? specs? With vista around the corner, another gig couldn't hurt
if not a good tester, it will come in handy