On most computers you can boot the PC while pressing the F8 key to boot
to the boot menu. Here you can choose "Safe Mode"
or Safe Mode With Command Prompt".
If your computer restarts constantly and never
makes it to Windows, and you think a virus might be the culprate, you can
boot to Safe Mode With Command Prompt and use this to manualy start your anti-virus
Prepair your Computer by adding a blank text.txt file to C:\ drive useing
Windows Explorer while your PC is OK. Name it "TEXT.TXT".Then if you need to run Antivurus
from DOS at boot-up, you can type this at the DOS prompt:cd C:\ (hit the ENTER key)
Then type text.txt (hit the ENTER key) When the text file opens, left click "File" at the top of the text window. Then left click "Save As". When the Save window pops up,
left click the down arrow to the right of the "Save As Type" space.
Left click "All Files" and scroll through the "Save" window to the location of the antivirus .EXE file (usualy in the folder named after the AV program).
Then you just "right" click the AV program and choose "Open" in the pop-up list.