If you have not already done so,I suggest:-
1. run up to date anti virus sofware.
2. Download latest patches for you operating system from Microsoft.
3. Download free firewall from ZoneLabs which will warn you if your computer is tryin to redial to a premium rate number.
4. Do not open email attacments from unknown senders.
5. Do not accept program downloads from dodgy sites
6. Do not link to sites from emails as these could be bogus.