Problem with USB Modem in XP Pro SP2

Hi
I am from India and I use the internet facility of Tata Indicom using their CDMA 1x USB Modem of Sungil.
The modem was installed on my Win XP Pro SP2 machine and working fine.

Recently i formatted my machine since it had some virus issues and now everything is clean. i also have a a licensed version of Quickheal Total Security installed.

I installed the modem again but now it is giving me problems.

It disconnects after 10 - 15 minutes automatically but the double monitor connectivity thing shows on the system tray.

I get the following error at times:
09/08/11 23:04:53 CreateFile FAIL : ModemPort=\\.\SIT_1x_usbmodem #2 ERR:32 ERRMSG:The process cannot access the file because it is being used by another process.

I cannot disconnect.

I have to restart my machine to connect to the Internet again.

What is wrong?

Best regards,
Yps

Check that the USB isn't being shut off. Power options in Control panel is the easiest but there might be something in the BIOS as well. Altho formatting and installing the OS wouldn't change the BIOS.