There is a class of computer applications called TSRs (Terminate and Stay Resident) that may interfere with CBX driver function. The following TSR is an example of an application that is known to interfere with the operation of the Yamaha CBX driver:

EXAMPLE:  Palm Pilot TSR — This program communicates with the Palm Pilot via the serial port. If the Palm Pilot is assigned to the same serial port as the Yamaha CBX driver, close the Palm Pilot program and this should free the operation of the Yamaha CBX driver.