Modem Already In Use Problem Connecting To Internet

I am currently using nokia n73 device to connect to internet using Nokia pc suit using USB cable. I tried using another mobile phone and connected it through usb cable and its working fine.
Whenever i am trying to dial a connection it says Modem is already in use or not configured properly.
My laptop is dell inspiron, i tried contacting them. A repair man came to my house and checked my laptop for the problem. They told me that its not a laptop problem.
Then i searched online to get my issue sorted out and get to know that i am having some configuration problem in my pc..
How to change my configuration to get it properly working ??
Do i have to upgrade my pc suit ?? its working with Nokia 7600.
