I have purchased this modem for my Comcast Internet. I have a desktop and a laptop. Each time I change the connection from one computer to another, I receive an error message about the modem. I have to turn the modem off, wait for a few seconds, and turn on agai. Then it works OK.

What is the solution for this? Should I return the modem to the store? Should I work with Comcast to resolve this problem?

Get a router... plain && simple..
When you switch devices like that, you're applying a new MAC address and modems don't like that... lol.. so, just get a wireless router and your PC can have a hard connection while the laptop conbects via wifi..
$30 solution...