My computer has very viruses and when i download antivirus the window which is downloading closes it

tell me a free way to fix this problem without re-installing windows

My computer has very viruses and when i download antivirus the window which is downloading closes its self?pop up blocker

Goto Trend Micro web site and do a free scan.

Else u can download stinger from mcafee and scan ur pc for free.

If u cannot goto those sites then start ur pc in Safe Mode with Network option and then go.

My computer has very viruses and when i download antivirus the window which is downloading closes its self?systemworks

This virus is too smart. It also happened to my PC last time! Maybe that virus made a "backdoor" onto your computer that someone is directly controlling your PC. The guy controling it may have been stopping your anti-virus software downloads, and then corrupting you remaining anti-virus software installed on your PC.

I guess there is no more choice but to reformat your PC and reinstall Windows. That's what I did when my PC suffered from a serious threat of a trojan.
If none of the good solutions provided by the other folks don't work try to go to www.kaspersky.com, install the activex control and follow the instructions. Then, perform an online scan. Once the scan is done save the report somewhere in your file. Then, print the report (make sure the full path of all the infected files is shown on the print) and then begin to delete all the files manually. Viruses are like other programs, once you begin to screw the files that make them work they begin to fail in their main purpose i.e. screwing your PC.