A virtual machine cannot access the serial port or the parallel port on the physical computer (835356)

SYMPTOMS

On a virtual machine in Virtual PC 2004, when you try to access a device that is connected to a serial port or a parallel port on the physical computer, the virtual machine may not recognize or access the device.

When you try to select the Physical serial port check box or the Physical parallel port check box in the virtual machine settings, you may receive one of the following error messages:

There was an error trying to open the following COM port on your physical computer: COM1 or COM2.

There was an error trying to open the following parallel port on your physical computer: \\LPT1.

CAUSE

This issue may occur if any one of the following conditions is true:

The physical computer uses the serial port or the parallel port.
Another virtual machine has already captured the serial port or the parallel port.

Note Only one computer can use a particular serial or parallel port at the same time.

RESOLUTION

To resolve this issue, close the program on the physical computer that is accessing the serial or parallel port, or shut down the other virtual machine that has captured the port. After you quit the program or other virtual machine, you can open or capture the serial or parallel port on the virtual machine.

MORE INFORMATION

When you start the virtual machine with the Physical serial port option selected or the Physical parallel port option selected, the virtual machine tries to capture the serial or parallel port of the physical computer. If the parallel or serial port has already been captured by a program on the physical computer or by another virtual machine, the virtual machine cannot capture the port.

If the virtual machine captures the serial or parallel port, the port is not released to the physical computer or the port is not available to other virtual machines until the virtual machine is shut down.