OnTime Meeting Manager has problems loading/running after upgrade to Domino 8.5.1. The issue is not OnTime specific. See below:
DOMINO 8.5.1 AND EXTENSION MANAGER ADD-ONS
IBM has introduced some I/O performance improvements for logging with 8.5.1, which unfortunately had the
side effect that servers were halting when running custom server tasks such as OnTime, in the startup process.
But the good news is that IBM introduced a way of turning this new logging off and reverting to the way logging was done in 8.5.0.
So all you have to do is put in an extra line in the notes.ini of the
Excerpt from the OnTime Meeting Manager newsletter 11/09.