• PC World
• »Computers
• »Desktops

Problem: You're inundated with pop-ups when you boot your PC.

Likely Cause: Spyware or adware.

The Fix: This problem may not be pretty, but most cases aren't terminal. Here's how to recover:

1. Unplug your PC from the network (or disable your wireless connection).
2. Boot in Safe Mode by pressing the key you're prompted to during boot-up (often <F8>).
3. Run a complete system scan using your antivirus software. Then run both Ad-Aware and Spybot, and fix all the problems these antispyware apps uncover. Restore your Net connection, reboot, and run both programs again after updating them with the latest definitions. Also consider using an online virus checker, such as one from Symantec. (See Privacy Watch for cross-checking online virus scanning services.)
4. If you have a truly nasty infection, chances are the prior step helped but didn't fully solve your problem. (And some spyware can even wreak havoc in Safe Mode, preventing antispyware apps from running.) HijackThis is your next step: It's a specialized application for determining exactly what's trying to gain control over your PC. HijackThis produces a log file that you'll probably find to be gibberish. Post it online at one of the forums listed on the HijackThis page. A volunteer adviser will offer help on cleaning up your specific infection, usually within 24 to 72 hours. If you're in a rush, get an automated analysis of your HijackThis log (you may still need a person to tell you which specific tools to use on your PC). (Also, see our slide show on using HijackThis.)
5. If all else fails, try using System Restore to roll back your OS. If that doesn't work, you'll probably need to reinstall Windows. But exercising patience when going through the prior step and following advisers' tips is almost always successful.

How to Avoid It Next Time: Use common sense. Don't click on strange attachments, pop-ups, or links on dicey sites. Raise IE's security settings (go to Tools, Internet Options, Security) or switch browsers. Keep your antivirus and antispyware programs up-to-date. Turn on System Restore. Disinfect your PC at the first sign of trouble (spyware tends to snowball). And save current copies of your security apps on a thumb drive or CD for easy access.