If I were to bet, my money would be on one of the NIC/cable combinations. If one or the other is bad, that computer will start continuously resending packets til it swamps the network.
Here are a few of the causes of sync errors I have found through hosting over 100 LAN parties.- NICs are the most common cause of problems in my experience, and I saw a site somewhere selling 10BT NICs for $7. My first choice would be replacement. That's a cheap and fast route. FWIW, I only get a year or so out of a NIC before it begins to get flaky on me.
- I once bought a "professionally made" Cat 5 cable that turned out to have a solid wire jack crimped onto stranded wire. Lately, I've been making my own cables. If you are all in the same building, you can probably even get by with satin cord at 10BT, though they recommend against it. Just make sure you use the right kind of plugs for the wire. And don't be afraid to spend six bits or a buck on each connector. In my experience, those packages of 100 for $10 really are too good to be true. I suspect they may be the out of spec rejects from one of the quality conscious manufacturers.
- I have also found one "bad" plug in one of my hubs. It works fine for most games, but fire up AoE or RoR and sync errors within 2 minutes, guaranteed.
- One other really weird problem I ran into once. I found that I had 2 cards with the exact same address! I didn't know that was possible, since they were from 2 different manufacturers, but the net would work fine until someone started the second machine. Weird!
There are a couple ways to proceed. First is getting up 2 machines and then keep adding one at a time till you find the culprit. However, since sync errors may take an hour to show up, this will take a while. I'd suggest that you just set up the whole net and have one of the machines watch for dropped packets to isolate the problem. If you have NE2000 compliant cards, there are a number of good LAN analyzers out there. BTW, I have had the best luck with ones that run in DOS without all the Windows overhead.
If you have problems finding an appropriate packet program, I'll help you find a link or email you one.
Keep your stick on the ice.