USB Modem connectivity issue

Hi,

I am using WindowsXp Professional edition with Norton Internet Security, in my HP Compaq nx7400 laptop. I have wireless internet connectivity which is working fine with Broadband connection. But having problems with Mobile Phone GPRS connection and USB modem connectivity. Some program is preventing the access to the external modems.

Any suggestion to resolve this issue? In fact, when I connected the Mobile phone to laptop first time, the internet got connected but after that getting messages like no modem found.

Thanks