so me and my girlfriend just got cable internet for the first time last night. took a while to get hooked up, because we had to call to register the modem she bought with comcast. just to clarify, we're not using wireless, we're wired to the modem. she registered/logged on using her computer, and then we tried using mine. it did the network adapter test and that was ok, but then it said there was a connectivity error, and we've tried a bunch, but can't get it to work. the light on my computer at the ethernet port is lit up, as well as the connectivity light on the modem. the only difference is that the modem light never flashes when connected to my computer, like it should if it's transferring info. I was wondering if anyone knows what might be up. I'm a n00b to the cable modem stuff. I usually have been able to plug my computer into just about any network and use the ethernet, so I'm kinda surprised this isn't working. is it because we registered using her computer, and now it won't recognize mine? I don't know what a router is/does, but was wondering if that might be what I need. please help!