I learned from my Information Security and Privacy class last September that one of the possible causes why your computer runs so slow is that your computer may possibly be infected by Botnet. This is a collection of software robots that run in parallel and automatically. I also read from one of the Technology Blogs in yahoo about what the signs are if your computer is attacked by Botnet and what to do if your computer is infected. The types of Botnet attacks are denial of service attack, Adware, Spyware, Email Spam, Click Fraud, and Fast flux. The worst one is when the hacker can log onto your every keystroke and steal your bank password, credit card numbers, and other personal information.