I have an Optiplex 780 USFF with Win7 64-bit system. I tried to replace the 64-bit OS with a Win XP since many program I am using is not supported by 64-bit OS. When I boot from the CD it gets as far as the Windows Setup "SETUP IS STARTING WINDOWS", then I get the blue screen with the following information:

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

If this is the first time you've seen this stop error screen restart your computer. If this screen appears again, follow these steps:

Check for viruses on your computer. Remove and newly installed hard drives or hard drive controllers. Check your hard drive to make sure it is properly configured and terminated. Run CHKDSK /F to check for hard drive corruption, and then restart your computer.

Technical Information:

Stop: 0x0000007B (0xF78DA63C, 0xC0000034, 0x00000000, 0x00000000).

Now I've scanned the hard drive and ran chkdsk and it shows no problems. Can some one help?

Thank you.