I have a client with SBS 2003. I was just kind of thrown into a situation without a clear answer as the precursors to the current problem. Where it stands now:
If I run the Exchange Connectivity test I get Exchange ActiveSync returned an HTTP 500 response. I tried re-running the CEICW and it fails on the E-Mail portion.
I tried recreating the virtual directories as defined in KB 883380. That did nothing. I was looking at the directory security for Exchange and noticed that I cannot click 'select' next to Default Domain and Realm. The option is grayed out.
I will be happy to post any logs or other info to help but I am out of options.