I too have been having internet connection issues. Vonage phone is disconnecting, Netflix is disconnecting, etc.Problems seem to start in early evening 4-6pm. My wife reports that netflix seems to work fine during the day. My speed test results via comcast site showing about 1-3 Mbs down 4Mbs Up and 20-30ms ping.
Download speeds seem to be the issue. Running hardwired to the router and cable modem. Will try going direct to the modem but it does not seem to be an issue with internal networking.
Issues seemed to start around new years...
http://stage.results.speedtest.comcast.net/result/389045024.png
Running speed tests on different computers produces similar results...
Others seem to be having similar issues recently...