Router Malfunction !

Hi ! Hope some kind soul out there can help me out with a problem that Im having with my Linksys WRT54G router (v3.1) with DD-WRT firmware.The Router is connected to a DSL modem.
I'm unable to connect to the router through the Web Browser - whenever I try to connect it shows "Limited Connectivity" and I'm unable to connect to the Internet too (I have to instead connect directly to the DSL Modem bypassing the router).I'm not sure if its Bricked because external LED display seems to be fine - Power LED is not Blinking / WLAN & Internet LED are on as well.

Now - here is the weird part - if I perform a Hard reset I'm able to access the router through the Browser (IP gets reset to 192.168.1.1), BUT if I make a change (for example disabling DHCP server or changing IP to 192.168.3.1) and click "Apply Settings" the router hangs & goes back to its earlier state of "Limited Connectivity".Has anyone experienced something similar ? Can someone please suggest what can be done ?
Thanks in advance !

if you don't post your

IP address
subnet mask
default gateway
DNS server

for both the WAN side and the LAN side of the router

we can't help you