I'm suspicious but that's my nature. Can you state what both of these fields (the ID and the related id field) data types are? By chance is one autonumber or long and the other integer, or both integer (because maybe you're not using an autonumber field for the parent ID field)? Overflow errors are most often caused by trying to put values in a field that are too large for the data type, or when running code and it tries to assign a value that is too large for the variable data type, or IIRC, also exceeding the boundaries of arrays, - things like that.
Monkeying with the registry for causes like that would be a bad idea. Or maybe they're not being straight with you.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.