[...] The #1 reason for computer slow down is the presence of malware or viruses. Malware is software which is installed on your computer, often without your knowledge, designed to display advertisements or otherwise generate revenue. When you notice your computer slowing down or performing oddly, the first thing you should do is run a virus scan and a malware scan. If you don’t have an anti-virus program installed, check out the free version of AVG. To check for malware, use Ad-Aware. [...]