Frequent Break-ups in Internet connections.

Hi!
I have MTNL's Triband broadband connection with UTStarcom modem. Earlier I was using it with USB connection. Recently I have switched to LAN card. Thought there is increase in speed, I am facing constant break ups in connection. Almost every minute. It's really frustrating. I bought new Intex LAN card which I fixed in one of the two PCI slots. Earlier I had LAN card but there was some problem with it. What could be the reason? Is the slot faulty? Or is it driver problem? Any advice is life breather!