Exactly the same thing is happening to one of my users. Opening the Exchange inbox or universal inbox causes the messaging app to crash about 1-2 seconds after opening it. I can see the full list of messages (which doesn't seem to update), and I can even open these messages, but the crash still happens, and dumps me back into the first screen of the messaging app.
This is on a Droid Pro running Android 2.2.1 (fully updated). If it makes any difference, we're using Exchange 2007 (enterprise), and the connection is secured with an exchange universal certificate.
The only resolution we've found is to delete and re-create the account. After this, the messaging app works correctly for 1-2 days, and then starts crashing again.
This may be coincidental, but the user reports the problem seems to start when she sends a message in a low signal area (going through a tunnel, in the subway, etc).
Any help is appreciated!