If your modem has a bad signal it could cause your problem. I would call comcast ask them to check your modem signals. If you lost connection for a second your router may not like it and disconnect.
I have Comcast broadband hooked up through a router to a desktop, and a wireless connection with another desktop upstairs.
Every week (or about every day, as is the case lately), the router will simply stop its connection to the internet, and both computers will be cut off. If I hook up the main desktop directly to the modem it works fine, which is how I know it's a problem specifically with the router.
I'll go through the whole process of setting it up again, and then a week later the same thing happens.
I've used several methods to reset it. Gone through the CD's setup, use SecureEasySetup (or whatever it's called), and used the NetSet utility. Same results.
And yes, I've made sure that the firmware is updated.
I've already replaced it once, but the same thing keeps happening. Could this be a coincidence? And BOTH are broken?
Or, is this possibly something deeper, like some sort of weird disagreement between Comcast and this brand of router?