You may experience problems concerning parallel port access on Windows XP (data access and interrupts). The reason for this is that there are versions of Windows XP that poll the parallel port to check for presence of devices.

The solution is to disable the writing to the port by modifying an entry in a registry:
[HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Parport\Parameters] "DisableWarmPoll"=dword:00000001