I followed my class hiearchy all the way up and indeed found an error in the classloc value at the top level class. It still referenced a relative location that was no longer valid. VFP never failed on this - evidently if the classloc fails, it searches the defined path for the class. I fixed the classloc and now the warning error messages are gone. Unfortunately, the fatal bonk is still there! At this point it appears the 2 issues may have been unrelated.