>I did set up a test which I ran over the network from two pc's in the same room. Each was adding 1/2 a million records with unique refs in exactly the way that our application does. They were all added correctly and there were no duplicates. I think I'll try it again though with 2 pc's in different buildings and see if that will recreate the problem.
>
>Phil.

Phil,

Maybe you can setup the test so that in between the fetch of the new Key and the append and replace in the other table, a few seconds "processing" (Inkey(3) etc.) occurs. Now look at the other PC and see how it deals with the FLock. Also, see whether the process can be aborted wrongly at the other PC. I mean, there will be some message, OR the user is allowed to press Escape (?). For that matter, don't use Inkey() but a loop of a couple of million, in order to make the "process" longer.

Regards,
Peter