I would opt to create a new user account and remove this one
But I've seen this problem with corrupt index.dat files
Not that this is your problem, but let's eliminate it
==Download and Install this small program
to help clean your temp folders,cookies, etc...
Windows Cleanup! 4.0Close all browsersOpen
Cleanup! by double-clicking the icon on your desktop (or from the Start > All Programs menu).
Click on the CleanUp button
When it's done
Reboot the computer
Restart into windows, may be a bit slower as we now cleaned the prefetch folder
That will increase on next bootup
Let me know how everything's running