Hi Paul,
It would be best to open a support ticket for this through MOAC. Please try and include any details from the information that Windows provides. Note you can find more details if look at the reliability report of your machine. You can then double click on one of the OC crash items and it should show you quite a bit of detail, which you can include in the support ticket.
As a note the problem is likely to be related to the process that OC goes through to connect to Exchange, this is why you see it start up ok, then stop after sometime as the background process of connecting to Exchange fails.
Regards
Ross.
Regards
Ross Adams - MSFT