I need help - I have a:
HP - s3323w Desktop
AMD Athlon(tm) 64 X2 Dual Core Processor 4800+ 2.50GHz
1.00 GM RAM
32-bit Vista

Just recently installed anti-virus software - AVG Free - Ad-Aware, let it run and walked away.  Computer shut down and this screen came up below.  I can't get into windows, and I can't even us the System Recovery - It freezes and won't complete.  I know a little bit about computers, but not much when I can't get into windows.  Here is the error message:

A problem has been detected and windows has been shut down to prevent damage to your computer.

A PROCESS or thread cruticual to system operation has unexpectidly exited or been terminated.

If this is the first time you have seen this stop error screen, restart your computer.

if this screen appears again, follow these steps:
Check to make sure any nbew hardware or software is properly installed.
If this is a new instatalation, ask your hardware or software manufactuer for any windows updates you might need.
If problems continue, disable or remove any newly installed hardware of software.
Disable BIOS memory options such as caching or shadowing.
If you need to use safe mode to remove or diable components.  Restart your computer, press F8 to select advanced startup options, and then select safe mode.
Technical information:
Stop:  0x000000F4 (0x00000003, 0x812D1D90, 0x86FB8CD4, 0x00000000)

win32k.sys - Address 86FB8CD4 base at 86E00000, DateStamp 4 549aea2

Any Ideas??Can you access the "Advanced BOOT Options" menu?  Tap the F8 key about once per second or faster as you restart your computer.

Reference(s):
    Windows Vista Advanced Boot Options - Troubleshooting modes
    Advanced startup options (including safe mode)My laptop went like that a few months ago. It loaded as far as just before the Windows Vista logo comes up and the screen went blank.

I just started it in safe mode, by doing as dahlarbear SAID, and did a system restore back to one week.

You should try this.
Now it won't let me start in safe mode.  I continuasly press F8, and I get a black screen (with my keyboard out), then a blue screen.

Any suggestions?You don't press F8, you keep tapping on it right after computer restart.