Hi,
As this is a single user system, not networked. It can only be the following.
1. A virus/trojan infection.
2. A security update gone wrong, corrupting the registry.
3. Does it have a firewall that is blocking access to the app.
4. Had similar problem on win2k workstation, where it had received a large spike, which didn't destory it, just after about a month it slowed down and refused to do some commands, upon close inspection I found that all the large capacitors were leaking.
The machine just slowed down and didn't throw many errors.

>>>Hi All.
>>>
>>>I have a problem site where our apps used to run but now no longer do. The user claims "nothing has changed" :) Anyway, after trying a few things and always getting the same result we wrote a one line program to display a messagebox() only. Compiled to exe and tried to run it. Same result - a message box pops up (not ours) with title "Program Error" and message "Invalid path or file name". Buttons Cancel, Ignore, and Help. None of these help - the program crashes with c5 error.
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>>Jos, I would check that the user(s) has rights (read/write) into whatever folders you use as RESOURCE/EDITWORK/SORTWORK/PROGWORK/TMPFILES/etc.
>
>Hi Hugo. I forgot to mention that this is a single users PC, not over a network. I have checked that he has a valid temp folder (rw) and the appropiate environment variable pointing to it. I have checked rw status for all required folders. But if even a single line VFP app will not run it implies something in the VFP and/or OS environment. Of course something has changed, could be trojan or spyware. :)