DHCP not working

I recently managed to update my old Win XP Laptop to SP2, and I had hoped it would solve this problem…

In my LAN, most computers have a static IP, but when I take my laptop to a hotel or a hotspot, DHCP often fails to get an IP address. I have to disable the network connection and re-enable it, and sometimes that works.

IPCONFIG /renew does not work either, it shows an error message which I don’t remember, and I can’t reproduce it right now because it seems my wireless setup on the same laptop died on me (it claims Wireless Zero Config service is not on, but it is, and there is no other program controlling my wireless anymore… oh well).

Are there any files that I can replace or (re-)register to get DHCP back working?

Thanks!