I had something similar happen last week ... forget if it was SpyBot or another program.  I did a search for the problem it was describing.  One of the links was to a "geek forum" where it was mentioned this was a new varmit and most anti- programs didn't recognize it yet.  It gave a recommended solution, which I followed and haven't found it since.

As I recall this one tried to hide in Microsoft Works, not Word or IE, or such, just in Works.