At first we were having problems when going to '/owa/' that the page was displaying blank. I found this page: http://www.petenetlive.com/KB/Article/0000429.htm
but it didn't really apply since this has been working for sometime (I did eventually try the suggested steps). After trying to access the '/remote/' app I received an error about the web.config file not being able to display errors, so I added the code to the web.config file as suggested and now I see this error:
500 - Internal server error.
There is a problem with the resource you are looking for, and it cannot be displayed.
It appears when trying to access any of the apps: /owa, /remote, /Exchange, etc. so there is something strange going on. I am not able to find any other diagnostic information on this problem. Any ideas on where to go next?
The server is a Windows SBS 2011 box that has been running for some time without problems. This error just appeared this week.