I have just posted another message about fixing this problem.

NT has a setting called opportunistic file locking. It caches things from the server and you software thinks it is getting the next number but it is not.

Turn this off and your problem WILL go away if you are using NT server.

Microsoft KB article Q129202 explains it. Find the registry key listed in the document and set EnableOplocks to 0 and reboot your server. Walla.. your problem will go away if there is not a problem in your code (is suspect it is not).

This is a fact. I had serious troubles from this problem and have not had another since disabeling oplocks.