Problem with Siemens ISDN Modem

I have a Toshiba satellite A100seires with windows XP home edition,I downloaded the driver of a Siemens ISDN modem,and when I connect to the net I find the laptop is connected for fue minites then restart by it self !!!!
N.B. That modem is working fine with all my other laptops from Toshiba satellite but not the 100 seires.What I shall do ?????