WRT54G DHCP client strangeness

I've had a Linksys WRT54G wireless router for about 4 weeks which has
generally been working well. However, a serious problem has just occurred
for the third time. I lose internet connectivity (LAN connectivity to the
router is ok). In the Internet section of the router's Status screen, the
three DNS addresses are all 0.0.0.0, so it appears that the router's DHCP
client cannot pull the DNS address from the ISP's DHCP server. On the third
occurrence of this problem, the IP, default gateway, and netmask addresses
were also 0.0.0.0. The obvious first step is to release and renew the with
the ISP's DHCP server, but DHCP Release and Renew buttons are missing from
their customary place on the router setup screen entirely!

I am running the current firmware (1.30.7). If I bypass the router all is
well, so it doesn't seem to be an ISP problem.

I can solve this by resetting the router to factory settings--the DHCP
client can pull all the addresses, and the release and renew buttons return.


TIA
Cliff