D link dsl-300T

hi
i have a d link dsl 300t ethernet adsl modem, and i cant seem to access
its setup pages.
the manual tells u to plug it in, and type its ip into iexplore, but i
just get the message "web page unavalible whilst offline"
also if i set my tcp/ip settings to "automaticly detect ip address" i
get the bubble kindly informing me that i have limited or no
conectivity. So i have set the ip, subnet mask and gatway to wat it
should be and this got rid of the error. i did enable the DHCP watsit
but the fact still remains that i cannot access the modem itself throug
internet explorer. I cant think of what to try next, ive tryed useing a
diffrent network card so its not that. the modem is brand new so its
not that either.

any help much appretiated

simon