Error on reinstalling Exchange Server 2003

I recently installed Exchange Server 2007 SP2 on my Windows 2003. I re-installed it because I upgraded my Operating System. At first it works fine with OWA. But now it’s giving me a headache! My Exchange Server 2007 is giving me an error "object reference not set to an instance of an object. At line:1 char:23.” I can access OWA but it seems that the changes with the settings is causing the issue. I also tried connectivity test on Outlook Auto Discovery and they work perfectly fine. Does Microsoft .net framework 2.0 Service Pack 2 have to do with this? I am lost here guys please help me.
