Such errors typically occur when the Windows Account assigned to the ipMonitorSrv service is not allowed to impersonate the Windows Account being used by Credential assigned to one of the Monitors.
The first thing to verify is that the Windows Account assigned to the ipMonitorSrv service is not the same Windows Account assigned to the Credential being used by the Monitor. This would be considered double impersonation.
The second thing to verify is that the Windows Account assigned to the ipMonitorSrv service is listed within the following User Assignments under Local Policies:
-Bypass traverse checking
-Log on as a service
-Replace a process level token
You can achieve this by proceeding with the following:
1. Run the ipMonitor configuration utility (ipMonitor\ipm9config.exe)
2. Click "Service Settings" and note the account selected here.
3. On the ipMonitor system, open "Control Panel -> Administrative Tools -> Local Security Policy".
4. Branch open "Local Policies" and click "User Rights Assignment".
5. Double-click the above-mentioned policies and add the account noted on step 2.
6. Once the account has been added to all policies, right "Security Settings" in the left hand pane and click "Reload".
7. Restart the ipMonitorSrv service.
8. Log back in and see if the Exchange server Monitor is still failing.