IP CONFLLICT

hello

i am using a DSL cable modem
and i was sharing my connection through a switch with 4 others system, previously we all were able to acess the internet directly .
by DHCP we all being granted a different IP address while each n evry one connect separately through modem.
but now it is showing “” windows system error
there is an ip conflict with other system ”

and now only one system get the ipaddress at a time .
so help me how can we share the connection without proxy setting

thanx