Very Computer

I have a Mitsubishi Amity VP sub-laptop computer onto which I have loaded
OpenBSD 2.9.  This machine uses an AMD 5x86 processor and has 16MB of memory.
I have a 3COM 3C589D PCMCIA ethernet card installed which is connected to a
LAN.  The machine boots and runs fine except that the ethernet connection will
only stay active for a few minutes at a time, after which it simply stops
working-- no panics, no errors, no log messages, and no packets!  If I shut
down and re-start the ethernet interface with the following commands:

# ifconfig ep1 down
# ifconfig ep1 up

then the ethernet connection starts working again (for a few minutes.)

Just for grins, I tried running the 2.8 kernel instead, but it does the same
thing.  I have also tried two different ethernet cards with the same result.

Any suggestions?

Thanks,

--Douglas Mandell