The first thing I'd do is run a virus scanner to see if this could be root cause. Here is a list of free malware and free spyware options, run one from both sets- delete any infections.
Free malware/virus Scanners:
Microsoft
_http://onecare.live.com/site/en-us/default.htm
Use Full Service Scan
Symantec:
Works in Safe Mode and free:
_http://security.symantec.com/sscv6/WelcomePage.asp
Trend Micro
_http://housecall.trendmicro.com/
Free Ad-ware/spyware Programs:
Ad-aware
http://www.lavasoftusa.com/
Spybot Search and Destroy
http://www.safer-networking.org/
* This is a great multipurpose tool as it will do both spyware and malware, and also has a small footprint.
Second thing I'd do is run system file checker to repair missing files. Here's how:
Running the System File Checker…
* Put the OS disk in the drive so that system file checker has a chance to fix issues if they exist:
1. Click Start, click All Programs, click Accessories, right-click Command Prompt, and select Run as Administrator.
2. Click Continue or supply Administrator credentials if prompted.
3. In the Command Prompt window type the following, and press Enter:
sfc /scannow
4. You should see the following on-screen messages:
Beginning the system scan. This process will take some time.
Beginning verification ph
ase of system scan.
Verification % complete.
5. Once the scan has completed you will receive an onscreen message resembling one of the following:
…found no integrity violations
…found corruption but repaired it
…found corruption that it could not repair
6. Please reply with the completion message that you received.
Refernce:
http://support.microsoft.com/kb/929833
Let us know the result,
Steve <> Microsoft Partner