inernet

I have Utstarcom modem (UT-300R2U)...... Internet works fine over Ethernet ......... but as I connect USB simultaneously it gets frequent disconnections every 5-6 minutes. I tried USB on another PC but same problem. It works perfectly fine if I use Inernet over Ethernet.

Any 6030 user plz tell me that it is having an internal modem or not?? I know that 3120 and 3100 dun hv modem so can't be used to connect to Inernet, How about this 6030 ??