I have been looking up your problem on google and found this information here
suggest your problems could
be malware related. Are you upto date with your service pack? You can try following the steps suggested in the link and see if it helps. If
it turns out your problems are malware related you should post in the HijackThis forum and see if you can get help there.
You could also try getting in touch with the staff at DoctorWeb to see if they no anything about your problems, hope this helps you.