Do you have any other reasons to suspect malware? Try an online scan with Bit Defender and let it quarantine whatever it finds. Suggest you run whatever security programs you have now on your computer in safe mode. Do you have Hijack This installed on your computer? You can install it from a CD if you can't get online in regular mode.http://www.pcworld.com/article/126459-1/article.html
The Hassle: My PC freezes periodically. How do I unfreeze it without losing my work or having to reboot?
The Fix: In Task Manager, select the Processes tab, choose Explorer.exe, and click End Process. (Just ignore the scary message.) Select File, New Task (Run...), type explorer, and click OK.
The Hassle: Your advice helped me unfreeze my system--but it keeps happening, and I can't go on like this. What now?
The Fixes: Start with the usual suspects: Scrub your Temp and Internet cache folders. Then run Windows' Check Disk utility with Automatically fix file system errors and Scan for and attempt recovery of bad sectors checked. (Open My Computer, right-click the drive, select Properties, choose the Tools tab, and click the Check Now button under 'Error-checking'.) Also, send your antispyware and antivirus tools into action.
No luck? Try getting rid of damaged ActiveX programs. From Control Panel, choose Internet Options, the General tab, Settings, and View Objects. Right-click to delete any items marked 'Damaged' in the Status column. You might have a corrupted file, so run System File Checker to verify (and, if necessary, reinstall) those files on your system: Click Start, Run, and then type CMD. In the command window, type sfc /scannow and wait awhile; the scan seems to take forever to complete.
If your PC is still having problems, they may be more deep-rooted. You'll have to try a few techniques to figure out which program or process is causing the freezing. Sysinternals has three superb free diagnostic tools. FileMon gives you a real-time view of every running program and lets you know what it's doing, recording and time-stamping each action an app takes; watch for a specific program's behavior just before a freeze. RegMon does the same for the Registry, while Process Explorer does the dirty work on Windows processes.