A system I'm working on creates default values for a primary key field by calling an external program that does a lookup into another table that contains the highest keys for each table.

Sometimes, randomly, the default value for a table definition disappears, after which the next created record in the table will get a blank value for the primary key.

So something is detroying the entry in the the DBC that contains the default. The loss seems random and unpredicatable, and has affected several different tables. I do not know when the error occurs until and add to a table fails.

I'm using SDT, and think it may have some connection with the problem - or maybe it's some kind of bug in VFP 7.