Internet connection failure

A quick look seems like the computer's are not receiving an IP address from the DHCP server built into the modem.  Try a full power cycle by removing power from the modem (including any battery if present) for 1 minute and powering off the desktop.  Once the modem has started back up and all the lights are flickering again (about another minute) then power on the desktop and see if it will give out an address.  You may need to haev comcast see if they can access the modem to reset the DHCP functionality if it somehow got changed.  

A full power cycle often fixes this common problem.  

The first part sounds right about not receiving address but I am replying with same modem with my laptop. I had Comcast tech here last week and there is nothing wrong with their hardware.

I just re-read my initial and I can see I may not have been very clear. The diagnostic file is from Dell D610 laptop. The common issue between desktop and laptop seems to be my copy of XP PRO. I don't know if that is the problem but I have the same issue on both computers I have used it on. I got it when I bought the Desktop used and can't verify if it's legit or not. Thing is, I have used this for 1 and a half years with no problem. I have spent 2 days Googleing this and have found many similar posts but none are answered to to the questioners satisfaction. That is why I decided to subscribe to Experts Exchange.

Try setting a static IP address on the laptop or desktop.  Check your network settings for the computer that is working and change the IP address by 1.  ie: if the working computers ip is 192.168.1.100, then make the laptop or desktop static to 192.168.1.101

If DHCP is the problem...then this will work and will let us know.  You should then be able to connect to the internet.  

You can also do a test ping one you have set the IP to static.

start/run  type cmd
Then when the command prompt comes up, type ping 4.2.2.5  (a common Internet IP I use for testing)

If it returns then you are online.

Thanks, I'll try this in the am. I may need some help though. I already tried setting the address to the same address as working laptop. I am just unpluging ethernet cable from one and plugging it into the other and that didn't work. I used the same address though, without adding 1. See ya in the am.

Ok, wait.  You only have one ethernet cable coming out of your comcast modem?  Are there any additional empty ports?  I think if that is true, then you are going to need a router of some kind.  I have Verizon DSL and they dont let you just pull the ethernet out of one machine and into another.  I would have to call them so they can clear the MAC address assigned to the computer and switch it to the other computer.  Of course, I just added a router to it instead and had them switch it to the router...then you can connect multiple pc's with no problem.  

Let me know if this sounds right or if we were on the right track before.

Ya know, I would have thought the same thing but while the Comcast tech was here and we determined that there appeared to be nothing wrong with the modem, he saw my laptop and asked if it worked. I said yeah and we fired it up, he plugged in the cable and opened up Google. I had tried to use the same cable on it months ago and couldn't get it to work. I figured that maybe they weren't allowing it but, I couldn't rule out that I just didn't have it set right. This gets more and more mysterious. I have seen this same problem though, on many forum sites and, like I said, I haven't found a successful resolution yet.

Having nothing wrong with the modem and it being able to switch between MAC addresses are two very different things.  I would probably try the static thing (although it kind of sounds like you already did) and then call Comcast and see if they can tell you what you would need to do to connect to another computer alltogether.  It's possible that you have a ghetto version of XP you are putting on the machine...but more likely it's the modem not giving out IP addresses.  

Let me know what you come up with in the AM

Morning authen-tech. I called Comcast this morning and asked about transferring net from one computer to another and they said no problem. When I first got this computer from my daughter, I went to Dell and requested CDs. I got an email this morning that they would be here tomorrow. (I'm impressed) My new computer should be here today so one way or another we'll find out if the XP Pro version I used is the problem or if it is something more sinister. I will get back to you when I find out. Next question will be getting XP Pro onto my new computer. It comes with Vista obviously so I will have to set up a partition and I have never done that. Thanks for helping out.

Ok, will wait to hear from you.

OK, this is really no surprise. It was the modem from Comcast. I was pacing around thinking I needed to get back to the lowest common denominator when I saw a comcast truck at my apartment complex I went out and waited for the tech to come out. I explained the situation to him and he immediately suspected the modem. He agreed to bring a different one up to my place and when we plugged it in it flashed a couple of times and all of a sudden I had network connection. He explained that maybe a few of the techs were not the brightest bulbs. Really sorry to have bothered you with all this.
My new computer got here yesterday. Dell XPS 420 with preinstalled Vista. Hate it already. I just hooked up my new modem to it and again, it works just fine. Now I need to get it set-up to dual-boot XP Pro. I spent a long time last night looking around. Wouldn't you think that this issue would be easy to just find a direct answer and step by step instructions? I mean, I know that many serious users are unhappy with Vista. Anyway I am going to look here and post a new question if I can't find a suitable answer. Many thanks for the time you spent. Can we call this solved?

Mornin' authen-tech. Casn we call this solved and award you points? Also, any further info on your ulitimate and virtual and easy statement?