Exchange 2007 keeps failing

Every other morning this week we got a message on the client "The Microsoft exchange administrator made a change that requires you to quit and restart outlook"
This coincides with no messages going in or out of the organisation. (Even though Outlook says connected)
This server is running as a VM on ESXi 5.5 hosts.
Can anybody help?
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Verify if the time between the DC and Exchange server is proper.
Check event viewer for any errors.
HKFueyAuthor Commented:
The time is spot on with the DC.

Getting error 2003:
The RPC over HTTP Proxy component is not installed or is not configured correctly. Use the Windows Component Wizard to add the RPC over HTTP Proxy component to the Networking Services.

Getting connection error 16025, but think that's related to the restart this morning.

And error 1000:
Faulting application name: kmain.exe, version:, time stamp: 0x4a8719ed
Faulting module name: kmain.exe, version:, time stamp: 0x4a8719ed
Exception code: 0xc0000005
Fault offset: 0x0000c868
Faulting process id: 0x7cc
Faulting application start time: 0x01d0aa53c0ac5bf0
Faulting application path: C:\Program Files (x86)\eXchange POP3 6.0\kmain.exe
Faulting module path: C:\Program Files (x86)\eXchange POP3 6.0\kmain.exe
Report Id: 0edc2c2c-1647-11e5-af8e-0050568c6220

And this (1005):
Unexpected error The local machine must be a Kerberos KDC (domain controller) and it is not. ID no: 80090339 Microsoft Exchange System Attendant  occurred.

And a few of these (1016) prior to fail:
Exchange ActiveSync has encountered repeated failures when it tries to access data on Mailbox server [MYSERVER]. Exchange ActiveSync will temporarily stop making Exchange ActiveSync requests to the Mailbox server. The process will be postponed for [60] seconds. This may be caused if the Mailbox server is overloaded. If this event is frequently logged, review the Application log for other events that could indicate the root cause of performance problems on the Mailbox server specified in the event description.

And also this (9690):
Exchange store 'First Storage Group\Mailbox Database': The logical size of this database (the logical size equals the physical size of the .edb file minus the logical free space) is 258 GB. This database size has exceeded the size limit of 250 GB.
HKFueyAuthor Commented:

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HKFueyAuthor Commented:
I have followed the steps, increased db size and created a new mailstore/db. If that solves I'm happy.
HKFueyAuthor Commented:
I followed the steps in the link and am now sorted. R--R gets points for suggesting looking in event log!
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