Loses Internet Connection

I have Comcast Internet service running with one one cable modem and no router. My connection to the Internet will go off while I am listening to streaming music or playing an online game that continuously streams data back and forth to the online servers. The only way that I get back online is by either restarting my computer or running Comcast Desktop Doctor which refreshes my DHCP settings. It also tells me that my Network Card is incorrectly configured to accept fixed ip addresses instead of dynamic addresses. Well, after I run it, it says that it reconfigured my network card but not long after, I still get that same problem. So my problem is after "heavy" network traffic, I lose my Internet connection. These problems have just recently started. I know that i don't have a virus because I reimaged my machine and put virus scan on it. I also had Comcast cable come out and run some tests on the modem and connection and nothing was wrong on their end. I have also tried disabling my firewall but that didn't help either. So my question is what is the problem, why do I keep losing my connection when there is a certain amount of network traffic and is there a fix for this? Any help is greatly appreciated.

jmoore00