This means that your parallel port is a bit too fast and you need to self adjust the "Pulse Delay" of the Portman 2x4 driver. Go to the Control Panel | Multimedia | Advanced | Midi Devices and Instruments. Highlight Portman 2x4, click Properties | Settings | Advanced. Add 10 to Address Delay and the same amount (10) to Data delay by incrementing up (you may have to experiment with a few different setting values). Click on Ok, then restart Windows. If you see that the error message is gone then you've fixed the problem. But if you find that you've got some stuck notes or other strange occurrences, then go back and add another value of 5 or 10, etc, etc.