Dropped Packets

[Dave Raven]

Hi all,
	 I have a FreeBSD 4.11 (I know its outdated but I don't have an
option) box which is behaving very weirdly. After about a day and a half it
starts to drop packets - about 6-10% of pings at least, and tcp traffic
becomes unreliable etc. 

I have swapped out the network cards, the cables etc and I don't have any
mbuf problems and all seems fine. For the first day the box works fine -
pinging, doing tcp traffic etc; and then suddenly it just stops. Rebooting
brings it all back to normal. 

Any ideas what could be causing this, and how I could go about diagnosing
it? As far as I know there are no known bugs for this. I'm using the em
driver, but not with SMP. There are no errors on the interface, and the em
debug_info and stats sysctl's don't show any problems - there is no
indication on the box itself that its dropping packets..

My thinking is that it must be box specific as a reboot solves the problem?

Thanks in advance
Dave