It doesn't matter, in release mode that condition won't be asserted, they aren't even compiled into the bits. You will not experience any problem from that whatsoever.

Sorry, I wrote the wrong term in my haste.  You are correct that we are seeing an assertion here, not a exception.  Either way, however, the behavior is incorrect.

I checked that method and while it probably should not be getting called (the AllowAllDayEvents feature was added after the original release of the control), I did not get an exception but rather a debug assertion. Furthermore, I saw no code in there that would easily explain an exception, and no changes that were tagged with a recent date, so I am not able to expain why you got an exception, nor do I think that updating to the latest service release will solve your problem. If possible post a simple sample demonstrating this exception and we will take a closer look.

Perhaps I spoke too soon...  You correctly located the parameter to turn off the all-day event area, but now all clicks in the ScheduleOwnerHeader throw an exception in UltraDayView.InvalidateAllDayEventArea.  Is this a known bug?  We are using the release version of 2008.3, but we will probably update to the latest hotfix of 2008.3 in thenext couple weeks.