Stop Auto Device Detect

I am running XP Pro on my Toshiba Laptop. If I plug my Garmin GPS into the
serial port and turn it on before I power on my laptop, WinXP detects a new
hardware device and installs the software for it when I turn on the laptop.
The problem is, XP detects some kind of serial mouse device and loads a
driver for it. When that happens, my GPS input causes the mouse cursor to
continuously jump all over the screen and I can can not control it. My
question is; is there any way I can stop XP from automatically detecting a
new device so this will not happen.
BTW, if I start XP and then turn on the GPS it works 100% and does not
detect any new hardware. Because of operating procedures, it is standard
practise to turn on the GPS first, let it acquire the satelite signals then
turn on the LapTop.

Thanks for any help

Richard