broadband time out

hey guy
this one is really bugging me...
i have a goa net broadband connection..
its actually given to a grp by lan...
but the problem is after every 5 min...
the net stops responding... and when i ping the server it gives request timed out.. i am the last one in the line.. the chaps before me are cruising through the net.......
its really bugging
when i am on messenger it doesnt DC also and i miss many messages...
plz help me........