Rtl8139 file transmission lockup

Hi,
   I'm using 2 RTL8139 cards (both are SMC 1211TX) on my linux firewall.
These are on a linux box with kernel linux-2.4.16.  Normal internet traffic
from my local LAN is fine.  However, when I'm transferring files off of the
linux box to a Win 2k box on the local LAN, the eth1 (LAN facing) interface
locks with a TX error (assuming it's speed related).

   I can re-enable the LAN with an 'ifdown eth1' and an 'ifup eth1'.  I
added a debug printout for a TX underrun, I think that's what's happening.

   Here's the result of thedebug line I added: "eth1:TxUnderrun, status
0008e52e."
   FROM: printk(KERN_DEBUG "%s:TxUnderrun, status %8.8x.\n", dev->name,
txstatus);

Any ideas? (rtl8139-diag info below)
Thanks, Sean Mullen

The following is info from the box when it's locked:
************** Rtl8139-diag **************
Index #2: Found a RealTek RTL8139 adapter at 0xec00.
RealTek chip registers at 0xec00
 0x000: 91bf5000 00009295 80000000 00000000 000aa52e 000aa52e 000aa52e
000aa52e
 0x020: 02f70010 02f71010 02f72010 02f73010 02f60000 0d0a0000 654c653c
0000c07f
 0x040: 74000400 00009c0e a6738e84 00000000 006c1400 00000000 0088c100
00100000
 0x060: 1100f00f 01e1782d 000145e1 00000000 00000004 000417c8 b0f243b9
8a36df43.
  No interrupt sources are pending.
 The chip configuration is 0x14 0x6c, MII full-duplex mode.
************** Ifconfig ****************
eth1      Link encap:Ethernet  HWaddr 00:50:BF:91:95:92
          inet addr:192.168.0.1  Bcast:192.168.0.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:12250 errors:0 dropped:0 overruns:0 frame:0
          TX packets:23003 errors:0 dropped:0 overruns:1 carrier:0
          collisions:0 txqueuelen:100
          RX bytes:777356 (759.1 Kb)  TX bytes:29408263 (28.0 Mb)
          Interrupt:11 Base address:0xec00

********************* Pre-lockup *****************
Here is the rtldiag before the lockup:

Index #2: Found a RealTek RTL8139 adapter at 0xec00.
RealTek chip registers at 0xec00
 0x000: 91bf5000 00009295 80000000 00000000 0008a04a 0008a04a 0008a04a
0008a04a
 0x020: 02f70010 02f71010 02f72010 02f73010 02f60000 0d0a0000 0cf80ce8
0000c07f
 0x040: 74000400 00009c0e 543a8729 00000000 006c1400 00000000 0088c100
00100000
 0x060: 1100f00f 01e1782d 000145e1 00000000 00000004 000417c8 b0f243b9
8a36df43.
  No interrupt sources are pending.
 The chip configuration is 0x14 0x6c, MII full-duplex mode.