Style Sheets and Browser Compatibility

I'm new to Dreamweaver, and I've noticed a problem with displaying
style sheets in Internet Explorer. I created a style sheet in
Dreamweaver, saved it, and applied it to various parts of my pages. In
the design view, everything looks fine. However, when I preview the
pages in Explorer, my style sheet changes do not appear.

For the record, I'm using Dreamweaver MX 2004 and Internet Explorer
Version 6.0. Any ideas how to fix this?

Thanks,
Michael