[doddsy]

it's hard to know. U could run hijack this and maybe find some info in the log from that. or have a look for odd processes in task manager.

my advice would be to get adaware se

http://www.lavasoft.de/support/download/

and spybot 1.3

http://www.safer-networking.org/en/index.html

update both and run scans.

see if that helps.

then get a good firewall and be careful where u surf and what u download (free stuff)