If your PC has gone abnormally slow, or it always complains that "your Virtual Memory is low, shutting down programs", or just hangs more often that usual even if you have no programs running - then you might have a virus, adware, spyware or malware that hogs your RAM.
Other signs of infections are unusual behaviors of your PC. You yourself know your PC best, but if you are unsure, check out for:
- weird captions in the title bar of your windows (usually browsers)
- programs you never installed that run on background (check this by Task Manager)
- abnormal behaviors with your hard drives; e.g. mouse has gone erratic, USBs cannot be read, autoplay has been grayed out, etc.
Major Geeks Forums has posted a DIY fix to get rid of those PC intruders. I highly recommend this because it's very effective. Word of caution: follow the instructions CAREFULLY.