Earlier I used Windows 7 and the modem used to work absolutely fine. Even when it disconnected it used to reconnect automatically without any trouble. But then I installed Ubuntu 11.10 on dual boot and set up the modem connection properly but the modem now disconnects much more frequently(eariler it disconnected once in 5 hours or so and after ubuntu in 5 minutes!!). Also once disconnected it does not reconnect even when i have checked the connect automatically button. I have to restart the system to reconnect it. Also then I clean installed windows and modem works perfectly fine again. What is the reason for this and how can I solve this? I really want to use ubuntu but due to this problem I cant.

Sorry for my poor English.