Microsoft has released a new version of mshtml.dll. Apparently there
was a problem with the one they released as part of the IE update
roll-up MS09-054 (974455).

Do not download/install this file if you haven't yet obtained and
installed the MS09-054 rollup.

The direct download link for mshtml.dll for IE 5.01 is he

http://tinyurl.com/yhdhook

The direct download link for mshtml.dll for IE 6 SP1 is he

http://tinyurl.com/ycph3ce

If you want to obtain the IE6 SP1 rollup (MS09-054) here is a direct
download link:

http://tinyurl.com/ygjyyc6