tcp connections blocked on a suse server (very strange)

hello.

i've a linux server with suse 9.1, running apache, nfs server, dhcp
server, etc. etc.
it works fine but after a week or two working, it looses its connection
to internet (it is behind a router) but... if i do a ping or something
similar taht uses ICMP to connect, it can connect (te conection is not
totally down), but if i tri to conecta to a web, or something like a
telnet to port 110 of any computer, etc (someting that use TCP) it
doesn't connect.
if i've running something like amule than use a lot of connections, then
the same happen but in spite of two weeks it last two or three days.

if i do a "network restart" i dont solve the problem ..... the only way
i've found to solve it is to restart the computer.

the same thing happended to me with the "same" server with suse 8.2 and
with a different hardware (we update the server hardware).

I'm absolutely lost :-(
anybode have any idea to help me?


TIA