can't type text into comment and message boxes

This may have been reported before...

This is the second time that I noticed this behavior on different
machines:
After launching Max5, I can no longer type text into comment and
message boxes (double-clicking doesn't bring up the cursor), while all
the other objects behave as expected.
Trashing the Preferences folder does nothing.
When I observed this for the first time reinstalling Max fixed the
problem, but it would be good to know what may be causing this erratic
behavior.

The only thing I did was changing ownership and permissions for a
folder inside the patches folder while Max was running, but this could
have hardly been the reason, I suppose.

Georg

XServe Mac OS X 10.4.11
Max 5.0.6