when i start using my desktop low vitual memory icon always appear,also when i'm trying to install programs like antivirus or office 2000 set up appears but when i enter the product key it disappear,also when i try to open run(msconfig) to configure my startup it will open but disappear again! nid help pls....

Virtual memory gets eaten up by programs running in the background. Try going through the steps on this site:
http://computeradvice.mikebinns.net
and they should help you clean up the unnecessary programs running in the background.