>>I assume you've already done something to try playing with SetErrorMode() to see if you can get the critical error not to trap out at the OS?
>
>Unfortunately, I don't know anything about it. Is it an API function?

Yes - it determines whether Windows traps certain errors or passes them along to the app for it to deal with:

---

SetErrorMode
The SetErrorMode function controls whether the system will handle the specified types of serious errors, or whether the process will handle them.

UINT SetErrorMode(
UINT uMode // process error mode
);
Parameters
uMode
[in] Specifies the process error mode. This parameter can be one or more of the following values.

---

My guess is if it's going to help, you'll want to pass it the critical error handler flag:

DECLARE INTEGER SetErrorMode IN Kernel32 INTEGER Flags
=SetErrorMode(1)

You can use this to bypass having the OS trap out I/O errors to simplify handling some tests for missing floppies, for example:

DECLARE INTEGER SetErrorMode IN Kernel32 INTEGER Flags
nOldValue=SetErrorMode(0x8001)
? DISKSPACE('A:')
=SetErrorMode(nOldValue)
? DISKSPACE('A:')