NMBCLUSTERS message occurs with an PCI ex0 ethernet card but does not occur
with a ISA ep0 card.

When using a 3C905B-TX (PCI, fast ethernet, full duplex) on
i386/1.5-release (Pentium 100, 32MB), I get frequent "WARNING: mclpool
limit reached; increase NMBCLUSTERS" messages. 

The system is a samba server and the samba clients (Win98, sip0) get
frequent "request timed out" or other error messages.  The system is not
usable as a file server.  Copying a 10MB file never completes.  10MB FTP
transfers to and from the same server seem to work without a problem.  

After installing an ISA half duplex ethernet card (ep0) in the system,
there are no NMBCLUSTER messages and the clients have a consistent ~500KB
transfer rates from the server.

Taking the same 3C509B-TX card and inserting into a Pentium 200 MMX
computer (32MB), the message "can't map i/o space" is displayed and the
device is not available.

I don't have any other PCI fast ethernet cards to experiment with that are
supported in 1.5-release.

Do you think the card is the problem?  If not, any idea where the problem
is?