- Slow performance
- Windows folders opening on startup
- Unprompted popups - watch out for Malware disguised as a malware scanner!
- Questionable search engines where your homepage used to be
- Warnings on your desktop about dangerous programs on your system
- Computer reboots unexpectedly
- Strange icons on your desktop or system tray
- New software on your computer that you didn't install
Please note: a slow computer or the "blue screen of death" does not always mean you have a virus! It could also be hardware problems.