David, I have gotten in to the habit of opening class libraries by first issuing:

clear all
release all
close all
set classlib to
DO (_BROWSER) WITH 'classlib' &&where classlib is the library name - extension not required

(this is in a program)

The crashes seem to occur less often. When I am into heavy manipulation, I will make a copy of the libraries every 5 or 10 minutes just in case.

I have had no serious losses since doing this although as I say, the crashed continue. Since I can't reproduce the crash at will, I haven't gone to MS with it.