I've been experiencing a problem with my exchange server over the last few weeks. At what seems like random times I'm getting notifications from my monitoring software that the HTTP service on exchange is not responding. When this happens no one is able to log into outlook web access. Regular Outlook clients continue to work normally and email continues to be sent/received but no one can log into OWA. I've tried resetting iis and also restarting the site itself but nothing short of a full server reboot fixes this. It tends to appear again after two or three days. I can't find any clues in the event logs and there have been no recent changes to the server. I actually resorted to calling Microsoft for support but they won't touch it because its running in VMWare. I'd greatly appreciate any help with this one.