Thanks for posting back. Just a suggestion....follow the steps given here
PROTECT YOURSELF FROM MALWARE: Tools & Tips
to be certain your computer remains secure from "invaders".

If you get something again like this Trojan.Zlob or other nasty items don't jump to reformat, these things almost always CAN be removed without reformatting by starting with the steps here

READ ME Before Posting A Request For Assistance!

and then posting the info and symptoms here
Spyware Central

and then one of us will walk you through any other cleaning steps which might be needed.
Judy