USB modems are a pain in the butt, always have been, always will be. USB just wasn't designed for networking, it uses far to much PC resource and it still thinks it's a dial-up connection. If you've got the money I would strongly recommend that you get yourself a proper ADSL modem/router and connect via ethernet.
If you don't want to go down that road, have you tried using the reset button on the modem, uninstall and then re-install the software?
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Do you know that we're all in line for succession to the throne? Really?
Well, if forty-eight million, two hundred thousand, seven hundred and one people died I'd be Queen.