> In at least one case it is related to the data in the table because if I skip the reload step above and add records to an empty table, then I don't see the problem. But I can also load that same ascii data to an identical table with a different name and I don't see the problem.

This actually may provide a clue. When I worked at Fox we'd run into really strange problems that ended up being the result of a high ASCII character in a field, program file, etc. Since the problem doesn't occur until you reload the data from the ASCII file, I'd suspect that there's actually something in the data that's causing the corruption.