Network connection periodically drops

For a reason I can't understand, when I'm using uTorrent to download a large file, if I later start playing a game like Borderlands or opening other internet programs like IE8 or Skype, my connection will eventually drop.

When I right-click on the Network icon in the taskbar and select "Troubleshoot Problems", this program will reset my network. It almost always says "Default gateway isn't available"; I've seen the message "Local Area Connection 2 doesn't have an IP configuration" but this is rare. Even one time I saw the message "DNS server isn't responding".

I looked on Motorola's site for any driver updates but didn't find any. The specifics of my modem are:

SURFboard SBG900
Software version: SBG900-2.1.15.0-SCM00-NOSH
Hardware version: 3

Is there something I can do to fix this issue?

well if default gateway isnt available then its the problem with the internet service provider so you need to consult the ISP and they can help you in changing the modem and provide you with the new internet connection