When I see the words slow computer and Comcast in the same post I always ask the following questions:
1) Do you have any Comcast software installed, specifically the Comcast toolbar? It can be very flaky, causing slow-down issues. If you do have it, uninstall and see if that helps speed up your computer. Included with the Comcast toolbar is Anti-Spyware Scanner powered by Computer Associates. You can remove this also if you don't use it.
2) What is the make and model of your Comcast modem? Check to see if it is listed as End-of-Life. You can find that info here
If you don't see your modem listed, check the box next to Show End-Of-Life Devices. If your device is listed as EOL you should replace it by exchanging it at a Comcast office or by purchasing your own.
Edited by Queen-Evie, 28 May 2011 - 11:11 AM.