Third PC connected but can't ping or access files

I have three PCs connected together on a single hub. All three PCs have windows XP SP 2 and no other firewalls/anti-virus. The PCs are not connected to the internet. I just need to share certain folders, so all three PCs can access data. Simple, right?

I have manually assigned IP addresses and subnet masks to each. I have manually run the 'setup a home or small office network' on each, and called the network MSHOME. I have disabled the windows firewall on all three PCs. I am logged on as administrator on all three PCs.

The IP Addresses and Masks are:

169.254.246.1 255.255.0.0
169.254.246.2 255.255.0.0
169.254.246.3 255.255.0.0

The first two PCs are working properly. Both PCs can ping each other (and themselves). I view workgroup PCs, and I see three icons, one for each PC on the network. I can access all shared files on either PC from either PC.

The third PC is troublesome. I can set up an IP Address and subnet mask, and when I unplug the network cable I lose the conenction. I can see the third PC from each of the other two PCs.

However, I cannot ping this PC from either of the other two PCs, and this PC can't ping either of the other two. I cannot OPEN the icon of the third PC from either of the other two, even though it is present.

I'm not exactly sure what the name of each PC is, but I know they are different. I'm going to try manually naming each, but I doubt that will fix this problem. It's got to be a minor permission or blocking issue.

Oh! one more thing: on the third (broken) PC, I've also tried uninstalling the network card via the Device Manager, and using auto-detect hardware to reinstall the card, and there's still no change. I've tried restarting each PC, unplugging the hub, and it doesn't make any difference. I've tried using 'configure IP address automatically', but that results in 'limited or no connectivity' on all three PCs, and I lose the ability to access shared files on each. I've also tried unsharing all files and restarting, with no effect.

I'm completely out of ideas, but it's got to be some stupid setting somewhere that I'm mssing. I'm open to any and all suggestions.

 

Could the network card be bad? I've been researching this problem since before posting my description, and I can't find anything even remotely like this problem. If the PC detects that a network cable has been plugged in, and allows me to set up an IP address, I should be able to ping in at least one direction, but I can't. The problem isn't on either of the otehr two PCs, because both of them can ping each other, and they can bothj 'see' the third PC, but can't PING it or access any data on it.

I've already arranged to get a replacement card tomorrow, just in case, but I'd appreciate any thoughts or comments. I'd like to know if I'm incompetant, going crazy, or dealing with something that is just really bizarre.

 

Where to begin...

There are a few details that I failed to mention previously.

I'm using a Switch, not a hub. I've checked each port on the hub, and they all work.

The two PCs that are working are right next to each other, while the third (that is not working) is farther away, but still less than 50 meters.

The Ethernet cable may not have been pinned out completely correct. All wires are connected to the right positions, but only two of them are all the way to the very end. The others are visible, but not quite to the tip. The cable does work (see below)

Finally, the Third PC is using a different network card than the other two.

Update:

I tried a new network card, put the third PC right next to the other two, and used a short ethernet cable. It could ping, and there were no problems!

Then, I moved the third PC to its proper location, connected the long cable, and my pings timed out! So, I put the old card back in and set up all three PCs right next to each other, and it worked... of course.

I'm so confused. I know the cable works, because yesterday I took one of the two working PCs, moved it to the long-distance location, and was able to ping the first PC.

So, here's what I've got:

Three PCs, two with identical configurations and the Third with a different configuration. The switch is right next to the two PCs.
When all three PCs are sitting right next to each other, all can ping.
When one of the two identical PCs is moved to a distant location (less than 50 meters), it can ping both the other two.
When the Third PC is moved to that distant location, it CAN'T PING!!!

It's not just the cable or the distance, because another PC can ping.
It's not just the PC, because it can ping when it is next to the others.

I need the third PC to be at that distant location, and I need to ping. What are some possible causes of this problem, and what can I do to resolve them?
Also, has anyone ever encountered something like this before?

 

"I'm using a Switch, not a hub. I've checked each port on the hub, and they all work." :confused

So is it a switch or a hub?

You said the RJ45 jack may not be properly terminated. Fix that, and you will eliminate one variable. Two pairs of wires are used in CAT5 network wire. You could have a jack that is working intermitantly.

E