Last I came across an issue which looking back at it was obvious enough, but not at the time:
I needed to export some mailboxes to pst files on exchange 2010 NOT SP1 using the EMS (Shell), so as you might (not) know you need Outlook x64 installed on the server where you want to do the export from.
No problem, I just installed outlook and proceeded with my exports. But then it turbed out that my BES Express which was on the same server stopped working. The BES Services wouldn’t start anymore.
So after some digging in the event logs it turns out that outlook overwrites the mapi32.dll file that you installed as a BES Prerequisite (MAPI CDO 1.2.1 pack).
-Uninstall outlook , then reboot the server.
-Then go to control panel –> Add/Remove programs –> select the MAPI/CDO pack from the list and remove it.
-Download the pack again from here
-Reinstall the pack
-That’s it, the BES Services should start now and you should be up and running again.