OK, guessing here, but at this stage I'd be worried about a rootkit or shell hijack.
Major system cleanup required - boot from a live CD and replace explorer.exe and userinit.exe
Then a manual clearout of all temp files, followed by a series of rootkit and virus scans
My concern would be that one of those pen drives was compromised
Last edited by Milo Minderbinder; 26th December 2012 at 22:16.