App installed at a shop to register sales.
Made in VFP 5.0, windows 95, installed on a standalone
At point of sale, new sale is added to the system on pressing ADD button.The app works well when there is a stream of customers.If there is a time lag of 2-3 minutes between customer, the next press of ADD button comes with error that the form from which it is invoked is not found.Sometimes the error is that the public variable 'NLEVEL' initialised at main.prg is not found. The error does not come every time, once in 3-4 days.
We have tried changing/removing/applying screen saver.But to no avail.The m/c also restarts SCANDISK when run, 10 times. The Scandisk runs ,screen saver comes up, I move the mouse,the scndisk screen comes upand so on till windows comes up saying it started the program 10 times.I Do not know whether the 2 error are related.

Please help us solve the error,
Thanx
Vidya