C:\Microsoft.pif

Hi I have a IntelP4 2.4 Ghz 845chipset ASROCK Motherboard. Win xp pro and win 2000. 1GB + 256 MB DDR RAM. 160 GB + 20 GB HDDs. My PC is plagued by Trojan-Downloader.Win32.Agent.qpv I have Zonealarm system suite. Its virus scanner quarantines C:\Microsoft.pif but it keeps coming back again. Tried searching in registry but no trace. This happens whenever I am surfing net using Win XP

Please help. Thnx in advance.