There are several possible solutions to this problem. Switching to Firefox, while a good idea, doesn't solve the IE problem, it's just an alternative.
One thing you can try is going to Tools > Internet Options, click the "Advanced" Tab and click the button that says "Restore Defaults". Then, on the "Privacy" tab, set the slider to "Medium", and on the "Security" tab, under "Internet", set that slider to medium as well (in both cases, you might have to click the "Default" or "Default Settngs" button to access the sliders). Finally, on the general tab, click the "Clear History", "Delete Cookies" and the "Delete files" buttons (check the box that says "Delete all offline files" that appears when you click the "Delete Files" button). After this, click OK, then close and reopen IE. If this rather complicated process doesn't work, you might find a solution on Microsoft's Knowledge Base.

Of course, you could still switch to Firefox...