Since you don't really know what's been done, do a check for spyware and viruses using the links below. I know you may have already done some of this and the steps in the links below will take a while, but please follow the procedures outlined.:

First, download, install, update, then run ALL of the free spyware removal tools below. Delete all spyware found:

Ad-Aware">http://www.lavasoftusa.com/support/download/]Ad-Aware