Using free tools to remove spyware
Start by running Microsoft's Malicious Software Removal Tool. This program is designed to search for and destroy only a small fraction of malware, but the ones it finds are the most serious strains of spyware and virus you can get.
If that program doesn't find anything, run the installer for Microsoft's Windows Defender (if it isn't already installed on your PC) and make sure that the program downloads its updates.
Then click the downward-pointing arrow to the right of the word 'Scan' at the top of the Defender window and choose Full Scan. If Defender finds malware, follow the onscreen instructions to delete the harmful files. This may require one or more reboots, because some spyware won't let you uninstall it while Windows is running.
If Defender fails to find anything, or if it finds spyware that it can't delete, it's time for a full antivirus scan.
If you're using an antivirus program that is already loaded on your system, make sure that it's updated. If you're using Avira Antivir PersonalEdition Classic, run the installer, and then reboot.
When AntiVir is running, you'll see an icon in your system tray showing an open umbrella inside a red square. Right-click the icon and choose Start AntiVir.
Click the Start Update link in AntiVir's program window, and when the update is complete, click the Scanner tab, choose the Local Drives option in the lower pane, and press the F3 key to begin scanning your hard drive. If it finds anything, AntiVir will pop up a dialog box.
Select either Quarantine or Delete to remove the suspect files that it identifies.