PRB: Unable to open device \\.\Ppshell

RESOLUTION

If You Use Parallel Port Communications

• The following device drivers must not be started: Parallel, Parport, ParVdm.
  
  You can check the status of devices on Windows NT 4.0 by pointing to Settings on the Start menu, choosing Control Panel, and selecting Devices.
• The PPSHell device driver must be started.
• The following registry keys must correctly match your parallel port hardware configuration:

        HKLM\SYSTEM\CurrentControlSet\Services\ppsh: Interrupt Vector
                                                     Interrupt Level
                                                     Port Address
  						

• Ensure that the hardware parallel port I/O address and interrupt request line (IRQ) do not conflict with any other hardware devices on the system.
• A second process, such as another instance of PPSH, may already have the device open. Only one process can access the PPSHell device at a time.

If You Use Serial Port Communications

• A second process, such as the mouse driver, Windows CE Services, or another instance of CESH, may already have the device open. Only one process can access a given COM port at a time.
• The Serial device driver must be started.