Enabling some modules breaks CSS for Internet Explorer

I have a recurring problem whereby I enable some modules. As soon as I do so, the page is not styled at all in Internet Explorer 7. It is fine in Firefox. I am running Drupal 5.7. I can make a list of the modules which exhibit this behavior but it seems to be a recurring problem with quite a few modules - Event, Organic Groups, png fix, Tasklist Advanced, and several others. It happens with different custom themes. AS far as Event and Organic groups, could it have something with importing style sheets? Needless to say, it is very aggravating.