Oh, and it will add itself to old system restore points, so restoring to that won't help.
Lol don't tell me that.. It seems to have disappeared after a restore, Mcafee or ESET didn't pick anything up again.. And everything is working as it should be, for the moment!
Cheers for the responses!
Last night I put some folders containing music files from my home laptop onto a USB stick to transfer onto my work PC which is something I've done dozens of times before. At work this morning I checked the USB stick only to find nothing on it. I'm now home and have checked the stick on my PC and the folders are there. Am I missing something obvious that would make them only visible on my home PC?