another with the same problem:
I have 5 computers on my network and the router and DHCP work fine. Even on this computer, DHCP was working until last week.
The DHCP doesn't work, so it uses the APIPA (169.254.x.y) address, which of course won't go through the router, so even the homepage hijacker died; so i removed it, and all the other cruft, even ran the above mentioned softpedia Winsock fix; still DHCP won't work. (i'm using the Alternate Configuration with fixed/assigned IP address to talk to the router to send this.)
DHCP is enabled on the devices (i have wifi and wired, neither can find the DHCP server) I'll try a sniffer next; but if anyone has more clues, please post!