linux box troubles

[Jim]

Hi, I'm new to the list but I've got a small problem.  I have a linux
box at home that's running slackware 8.  The machine has an AMD K5 100
processor and 64MB of RAM in it. The problem is that it seems to have a
limit of how much data it will let me move to it or from it.  Once that
limit is reached, the machine stops responding to anything that comes in
over the network.  I can't ping it or connect to it.  I also use it as a
firewall for my windows box.  When the linux box acts up, it stops
forwarding packets to or from the windows box.  I can log into the linux
box itself and it will let me run programs.  If the program is network
related such as ping, it won't work.  It won't let me ping the windows
box or anything on the internet.  This also applies to ftp, http,
whatever.

On the linux box I have running imapd, sendmail, httpd, ftpd, sshd,
telnetd.  It also has a 128MB swap partition.

I have a friend with a similar setup, better processor, same memory and
the same services running on his machine, but he doesn't have this
problem.

When my linux box acts up the only solution I've found is to reboot it. 
I've found if I reboot it once a day it doesn't act up on me.

Any ideas?

Thanks