freebsd stable - Nov 2004 - VIA Rhine II network card

I think that something is wrong with VIA Rhine II network device driver.
I run FreeBSD 5.3. Behaviour of network seems to be random: one time
everything is OK but a second later I can't connect to host in my local
network. But when I connect to other host, not in my network and then
try to connect to previous one everything is ok. Moreover it (usually)
takes really a lot of time to establish connection (I often get
timeout), but when it's set I've got a normal transfer rate. 

And it's not a problem with my local network, because on same computer,
but running Fedora Core 2 I didn't noticed any problems with network.

What should I do to give better information about problem ?

And sorry for my English, but I hope it's understandable.

It could be a full-duplex/half duplex mismatch issue. Try not to use 
auto-negotiation. You can set your interface to "fixed" full-duplex
(or
half-duplex) in /etc/rc.conf  You must match the setting with the other side 
of your connection (eg. your switch).

Zoltan