>>Definitely not file name collision because there's a strict naming convention for these files that includes a primary key value as part of the file name. And there's now code that ensures that if a file of the same name exists, we close it and delete it before creating.
>
>Just thinking... if there's a previously existing file, its deletion is actually passed to the OS, which may execute it in a separate thread. I've seen (long ago, on a slower machine) situations when the previous file would still exist at the time the new one was created - and when debugging it was impossible to re-create,simply because debugging give the other thread the time to complete its task.
>
>To check this, check in the logs if deletion is related to the error. I seem to remember that in such a case I wrote a loop where I'd try to fcreate() the file, and sleep a dozen milliseconds until it succeeded. Then I'd just fclose() the handle and go on.
>
>Note that "seem to remember" does not guarantee that my context is the same as yours.

Interesting theory. Easy enough to implement, if none of the other possilbities pans out.

Tamar