I can reproduce (Max 5.0.4, OSX 10.5.3, IntelMacPro).
It looks like if you enter a time that has already happened into [timepoint] it will bang instantly. I wonder, is that the intended behavior and adding a second timepoint is the bug that stops it or is [timepoint] not supposed to bang if you enter a time that has already past?
A bunch of changes were made to ITM for 5.05 while we worked on trying to get external sync working coherently. I apologise for things like this slipping through, we’ll look at it for the next incremental.