1. When an instrument drops out, save the song.
2. Click on File/Revert to saved. If it's greyed out, just briefly run the song or change something until it's available. Then click on it. This will load the song you just saved, but with all instruments working again. As long as you have 'Keep common samples in memory when switching songs' checked under 'options' on the EXS24 interface (under 'Preferences') the instruments do not have to load again and the song will be ready immediately.
This takes a very short time. No need to close song or reboot Logic.
good one, michael. maximum points to you for the first practical and helpful post on this topic. nice one.
as for the 'just d*mn fix it already!' crowd:
I've said this before on this topic.. bugs can range from being an obvious boo boo in some code or some conflict that gets missed in testing, easily rectified when found, much like fixing a typo when you proofread.
others, unfortunately, are heinously difficult to isolate, and this one has all the hallmarks of being one of the worst in this category. just look at the range of users that have experienced the problem, and then other power-users like blumpy who work day in day out and have never ever seen it, ever.
you gotta find the bug before you can squish it. and given that it could come from a random convergence of seemingly unrelated factors, it's not hard to imagine that the causes for this one are totally elusive and sneaky to find.
anyway, still it's no excuse after this long, and I for one hope that a beta testing team still does exist out there, somewhere.... and that they are sending debugger reports whenever this prob shows up.