Hi there.

Posted this in the Debian Forums originally, but it will probably be better off here... Sorry about that.

I'm a bit of a Linux newbie so bear with me

Anyway, yesterday I did an `aptitude upgrade` (Running Debian). Gave it half an hour or so to finish off. Then rebooted my box.
Now I can't maintain any sort of TCP connection to anything.

I can send and receive ICMP packets (ie. I can ping), and I can, it would seem, make TCP connections. But I don't appear to get any sort of response from them, or at least, not for a significant amount of time.
HTTP just dies straight off. Even using lynx/elinks as opposed to firefox. Links gets as far as 'Request sent' and just freezes, waiting for a response from the server.
Telnet will make connections. They'll go for about 30 seconds, then I'll stop being able to receive or send data. BUT the connection is still there! Only when I force the host to disconnect me do I get a 'Connection closed by foreign host'.

I'm perplexed. There is nothing in any of the logs that might lead me to the problem. The only two inklings I've had are NIS telling me there was an 'RPC Timeout'? I originally thought this (NIS that is) was creating the problem so removed it. The other inkling I have is that tcpdump seems to be telling me theres an awful lot of ARP requests bouncing back between me and my router.

I should point out this ISN'T a problem with my network. Windows works fine. The other 3 computers in the house are working fine... So I'm 99% sure it's Linux.

Does anyone have any ideas? Any help greatly appreciated.