ethernet won't get IP from dhcp

[pirpir]

hi
i have a laptop with xp pro. when I use my laptop at school, and plug in the rj45 cable, my ethernet card obtains an IP properly fro dhcp. However, when I try to do the same thing at home with my cable modem, I can't get a valid IP from the dhcp server. There's nothing wrong with my modem/cable or cable company since when I connect the same cable to my 98 desktop computer, it works.
I can get a valid IP if I connect using USB but I should be able to do so by using the ethernet card directly.
help desk operators from my cable company said there was a difference between getting an IP from dhcp at school ang getting it from dhcp at home and they told me to reinstall my driver, which didn't work..
if anyone knows why this happens, i will be glad..
thanks anyway..

 

[pirpir]

well, maybe this question should better be in the hardware/ethernet forum.
I'm sorry for posting it in the wrong place, i am still learning to find my way around here

 

[bcastner]

I have seen issues due to this:

http://support.microsoft.com/default.aspx?scid=kb;en-us;167014

Open notepad and copy/paste the below as dhcp_reset.cmd

netsh int ip set address "Local Area Connection" dhcp
ipconfig /release
ipconfig /renew

 

[percent]

What model/company cable modem do you have - not all modems have DHCP support - infact I have found that only until recent the companys have been selling modems that have DHCP built in.

 

[jmaddone]

A cable modem only allows one MAC address (number associated with NIC) to access the cable modem. So if you plug in one machine and access the internet and then unplug that machine and try to plug in a new machine, it will not allow the new computer to access the internet because it has a different MAC address. You must reset (unplug power and plug back in) the cable modem each time you switch computers or buy a router to share the internet connection.

 

[ravashaak]

If none of the previous posts apply, try temporarily resetting your NIC to half duplex, 10 Mb. Then try to get an address via dhcp.