I just cleaned up this mess on another computer with somewhat different results. In this case the W32.VIRUT.CF virus was spread to virtually every exe file on the system. Symantec went a little crazy in cleaning it and actually deleted explorer.exe and the registry entry to start explorer. The system would start but the screen was black. I opened taskmanger and realized explorer wasn't running. I tried to start it manually and got an error saying explorer not found. I had to copy the explorer.exe and userinit.exe files from another system to the Windows folder and replace the reg keys. [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon] "Shell"="Explorer.exe" "Userinit"="C:\Windows\system32\userinit.exe," I also found that numerous Windows files were missing. Many of the Windows program start menu shortcuts were linked to files in the winsxs folder instead of the program folders. I noticed this with windows media player, windows mail, windows DVD maker, internet explore and several other shortcuts. Rather than spend hours trying to find all of the missing files, I just chose to run the Vista setup again in upgrade mode..