Surely, Jamie, you have a decent antivirus program installed? AVG, which I have used for years, and Avast are both very good free ones, and they scan emails. Also, you need an anti spyware program. There are several free ones such as A squared free and Super Antispyware free. Collectively, these should stop problems like the one you have experienced. Also, use a decent firewall - the Windows free one is useless. Zone Alarm is free and very effective, though you may have to turn off the email protection if it clashes with the antivirus email scanner.