>A client is moving a FPW 2.5b app from Windows 3.1 to Windows 98. The app refuses to start, indicating an I/O operation error. At first, I thought the problem was related to the Divide by Zero problem experienced on fast, modern computers, so I had the client patch FOXW250B.ESL with DZPatch. Unfortunately, this made no difference. Does anyone have an idea what the problem might be?

If the message you get says something about WIN386 Watcom then:
You have to turn off hardware acceleration. I did this on a client windows 95
machine and it solved the problem.