did you every get this fixed?
I understand that Windows Explorer is closely linked to Internet Explorer so does your Internet Explorer work okay?
Unless you are unlucky enought to have had another problem, unknown to you, hit explorer at the same time as you changed the file name, I would think that you have an isolated case of file corruption that can simply be fixed by replacing the broken shellstyle.dll; however bear in mind that explorer is crucial to Windows. When you screw up explorer bad things can go wrong.
Hope you get it fixed.
If you are interested in any Windows "Howto" articles, try here:
http://www.findingfacts.com/L3/L3_1_5_12.php