IIS admin service keeps stopping

Our IIS service and WWW service keeps stopping without any logs being generated. I can start it and it will be fine again. After a few minutes it will stop again. I don’t have any clue where to start troubleshooting. My feeling is that it’s a problem with IIS4 because IIS admin and www services stops at the same time. We’ve been using it for the past 3 years and it’s only 2 weeks ago when it did this problem. The only change I made was edit the users of Exchange. We are using Exchange5.5, OWA and IIS4. Thanks for the help.