Boot problems with serial device

So,
I have a device connected at serial port and always on and sending data to
the port. When XP restarts sometimes it understands it as mouse put driver on
it and problems begin... Already tried fastdetect at boot.ini never helps -
before at NT was NoSerialMice parameter, now it is substituted by fastdetect
- but it never works.
Could you recomend me how to solve this one? Can I turn off serial checking
for mouse driver at all?
Thx,
Oleg