Since someone mentioned DDoS attacks, if you aren't too sure if your computer has been infected, you should try Trend Micro's new product called RUBotted. It's currently free since it's in Beta, and works great. Since the software is behavior based and not definition based, it does not require constant updates like Anti-Virus programs (which cannot guarantee that you aren't infected). It's definitely worth trying out, especially if you are the computer support guy for an entire family like I am http://www.trendsecure.com/portal/en-US/to..._tools/rubotted p.s. If you're wondering how it works, it watches the network traffic on your computer and does very well at determining whether or not the traffic is intent or not.