Try resetting Internet Options (Control Panel -> Internet Options -> Advanced tab, "Reset".
Now what this will do is this;
it deletes all temporary files (which is safe) and disables browser add-ons (which we probably don't need anyway) and resets all the changed settings (which should just go to default settings).
You will probably have to reset your Home page and other than that. if you are running dsl you may have to do a reset of the modem by turning it off and then back on. Other than that it shouldn't do anything else.
Try it and see.