ZAP is an exclusive command, which means the OS has to respond as well as VFP.

I suspect the OS is having the problem, not your code, and that could be network permissions, file ownership, etc.

reminds me of UNIX files created by root that accessed fine but could not be destroyed by users, whereupon the fox app gave weird results!

( FOX behind the scene doesn't do what you think it is doing, it may be creating new files, deleting the current and renaming, which is a problem if there are ownership issues ! )