I applied Windows 2003 SP2 to our exchange server (this machineis also a domain controller) box after it appeared through automatic updates. The install was successful but owa has not worked since. IIS is up and running as normal, and can be successfully restarted with iisreset. When we try to browse to the site we get "unable to display the page" message and on the server there is an application error "Faulting application w3wp.exe, version 6.0.3790.3959, faulting module comsvcs.dll, version 2001.12.4720.3959, fault address 0x00043231." with a corresponding error in the system events log "A process serving application pool 'ExchangeApplicationPool' terminated unexpectedly. The process id was '6420'. The process exit code was '0xc0000354'." I followed the steps in article 842493 to modify permissions but that made no difference. I have tried re-applying Exchange Server 2003 SP2, and have run Microsoft Update to collect 5 further ES updates, but the error is still happening just the same. I am now wondering whether I need to reinstall IIS - but that will presumably involve recreating the Exchange virtual folders also, and I am not familiar with that process. In any case I would prefer to know before doing anything that major whether it is likely to solve the problem.

It does sound like you have some version issues on your IIS files. This article describes the process: http://support.microsoft.com/kb/320202

Our OWA was working fine until W2K3 SP2 was applied, then OWA quit allowing logons. No errors as you have above. Try these steps, they work for my system. The steps are from a Microsoft document named How to manage Outlook Web Access features in Exchange Server 2003, and are from the section on how to enable forms based authentication, which we are not using currently. Repeat these on all servers in your System Manager. 1. Start Exchange System Manager. 2. If administrative groups are enabled, expand Administrative Groups. 3. Expand Servers, and then expand your back-end server. 4. Expand Protocols, expand HTTP, and then expand Exchange Virtual Server. 5. Right-click the Exchange virtual directory that appears under the Exchange Virtual Server container, and then click Properties. 6. Click the Access tab, and then click Authentication. 7. If it is not already selected, click to select the Basic authentication check box. 8. Enter a backslash (\) in the Default Domain box. 9. Click OK two times to close the property windows.

Sounds like you might have some issues surrounding the Exchange Server being installed on a DC. If possible, bring up a second exchange server, and make it a front end box. Have your OWA hosted on that. I don't think that MS recommends running exchange on domain controllers. If you decide to try and reinstall IIS, Exchange will fail. Your best chance for recovery from this is to roll back from the SP2 install first.