Your computer running slower than usual? Are you getting lots of pop-ups? Have you seen other weird problems crop up? If so, your PC might be infected with a virus, spyware, or other malware--even if you have an antivirus program installed on it. Though other problems, such as hardware issues, can produce similar symptoms, it's best to check for malware if you aren't sure. But you don't necessarily need to call tech support or the geek across the street to scan for malware--I'll show you how to do it yourself.
Step 1: Enter Safe Mode
Keep your PC disconnected from the Internet, and don't use it until you're ready to clean your PC. This can help prevent the malware from spreading and/or leaking your private data.
If you think your PC may have a malware infection, boot your PC into Microsoft's Safe Mode. In this mode, only the minimum required programs and services are loaded. If any malware is set to load automatically when Windows starts, entering in this mode may prevent it from doing so. To boot into Windows Safe Mode, first shut down your PC. Locate the F8 key on your PC's keyboard; turn the PC on; and as soon as you see anything on the screen, press the F8 key repeatedly. This should bring up the Advanced Boot Options menu; there, select Safe Mode with Networking and press Enter.
You may find that your PC runs noticeably faster in Safe Mode. This could be a sign that your system has a malware infection, or it could mean that you have a lot of legitimate programs that normally start up alongside Windows.