[plug] TCP connections refused

[Ryan]

This is a very very long story .. so I'll have to spare you the details
and explanations or you'll all hate me.

Debian box, after running for a few weeks, it refused all incoming TCP
connections to things like SSH/FTP/HTTP/SMTP/CUPS  nmap -F times out,
but it still allows UDP (snmp).  Still acts as a responsible gateway and
performs NAT for client machines.  It was power-cycled, ran for about 10
hours and then has done it again.  When it was running OK in those 10
hours, the ssh service did not run for some unknown reason.

Anybody have any idea what it could be doing based on the basic info
I've given?  It is a remote machine, and I can't connect to it any time
soon to see what is going on.

I'm guessing some dodgy RAM or something, has anyone seen this behaviour
before and could put a different slant on it?  There are no IDS things
running on it.

Thanks,

Ryan