If the scans do not find any malware, you can try running SFC /SCANNOW or use IEFIX, a general purpose repair utility for Internet Explorer which repairs Internet Explorer by registering it's core DLL files and reinstalls using the IE.INF file. It is suitable for Windows 98/ME/2000/XP.
Download IEFix.zip: http://windowsxp.mvps.org/utils/IEFix.zip
1. Unzip and double-click to run.
2. Click the "Apply" button.
3. You will be prompted for the Operating System CD or the Service Pack Files location:
* If you're using Windows 2000/XP, insert the Operating System CD. For OEM systems, point to the Operating System source path when prompted. If you've applied a Service Pack separately, you need to insert the Slipstreamed Operating System CD (if you have one) or point the installer to the ServicePack source path when prompted - i.e. "C:\Windows\ServicePackFiles\i386" or "C:\Windows\ServicePackFiles"
* If you don't have the Windows installation CD, and if the installation source files are not present in the hard disk, you may click Cancel. IEFix will continue with DLL registration part.
4. Restart your computer.