Solution:

This most probably be a software speed problem. The old application runs well in 486 system. However because system speed is increased. His application may have problem. You may test his application in other 586 PC such as PCA-6751. If it has problem also, then that is the software time out problem. I will suggest he test PCI interface, such as PCM-5868 on board PCMCIA. If PCM-5868 still not work, then customer's application is not possible unless modify programming.