It’s a bug in MSIE that was introduced to your system when applying the February cummulative security patch (yes, even security patches can bring new bugs :-X).

Fortunately, there is a hotfix that solves the problem.
Please see http://support.microsoft.com/?kbid=811630 .

All you need to do is download and install the hotfix from this MS page - that should fix the problem.

Vlk