OK DamianUK,
Time for some spyware hunting:
Apart from looking manually for the files Uk bob suggested,
Download and run Adaware:
http://www.lavasoftusa.com/support/download/
And Spybot S&D:
http://www.safer-networking.org/en/download/index.html
Make sure both apps are updated before you scan.
And here you can have your comp scanned for trojans:
http://www.windowsecurity.com/trojanscan/
Let us know how you did and what was found .
And as Uk bob allso mentioned , It is important to have a good Firewall and Antivirus running.