What patch did you apply?
I found a couple of lab cases that stated that corrupt entries in the Event log prevented it from being opened in the GUI
See if you can view the Eventlog file on your Cell Manager
Program Data -> Omniback -> log -> Server -> Ob2EventLog.txt
You may also want to get a directory listing to see when the Event log was last written to
Since the Reporting of Events is a function of 'omnitrig', first, make sure that it is running, from the MS-DOS prompt on the cell manager
cd \Program Files\Omniback\bin
omnisv status
and the current version of 'omnitrig'
omnitrig -ver
