What are typical indicators that your computer system is compromised?

There can be several signs of computer compromise from different sources. Though most of the time, there could be other explanations for impaired performance besides viruses, malware or other sources of interference, if you find files missing or deleted and you did not do it, the computer is running extremely slow or files are moved or changed then all these could be signs of compromise. The best way to be sure is to get a virus scanning program (there are free ones) and scan your system. It's also important to get and maintain (frequently update) an anti-virus program. You may obtain a free one from the related links below.