problem with dlink DIR600 router.......

hi

me and my friend share a internet connection, we have a dlink DIR600 router.
we do not use the wifi, we both have p.c's. we use lan.

earlier it was working fine but in last few days when i switch on the router the power and internet light remains orange. and me and my friends p.c's show red cross icon with "network cable unplugged" message.

but if i connect the net wire directly in my p.c net works fine.

pls help...