Dmitry,
Unfortunately this app is still in VFP6 too, so your values should be fine. Be sure to post back the actual cause of what's causing your classlib to disappear out on you.
I wonder if there is some code that is trying to "Push" the current classlibpath, install its own, then does a "pop" and it's not quite popping correctly.
What happens if you move your classlib in the path? Does it still get eliminated? If so it's a name based problem. If it doesn't and another lib gets whacked it's a positional problem.
>The len( set( "classlib" )) returns 1337 (and 1297 after "removing" my class library. Occurs returns 31 (and 30 after "removing" the classlib). I use VFP 6.0 btw, so maybe VFP 6 has lower limit.