I refer to the error in DOS.

I seem to recall having the error in Windows and it can be difficult to get rid of it, but that applies to a lot of Windows errors.

In DOS I usually find that Abort will get rid of it (like it is supposed to do). Fail and Retry can be useful though.

Oddly, on my HP 100LX a least, when accessing a PCMCIA memory card which it can't read, pressing Abort keeps repeating the error, whereas Fail cancels it and just switches to 'Current drive is no longer valid>'.