Viewing shtml pages in IE after XP Service Pak2

Hi, this is a bit off-topic but I hope someone here knows the answer.
After installing Windows XP Service Pack 2, now when I open .shtml
pages in IE, it's not displaying them as web pages but rather just
showing the actual source code in the browser. Is there a trick to
get this to stop happening? This doesn't happen with pages on the web
but only when I open these pages locally to work on them. Thanks!

Cliff