NICs don't seem to help.

[Gloryhound]

I have a four computer setup, one in a seperate building, three in one office, the three are using 3com 905cx nics and I have a 6 port netgear autosensing hub 10/100. The wiring was run to two of the computers by a third party. The one I ran hooks up 100 mbs no problem, the others show as unplugged at 100 mbs, set them to 10 mbs and viola they work. The cable run i did is longer that the other two. It seems to be the cables. disconnecting the comp in the other building does not affect the out come. I used three D-links in place and they did not detect the problem, however they wouldn't work at all the network simply didn't work with out clear errors. The questions I'm looking to get answered are these.

A) could this be my Netgear hub, which I've tried different ports for each computer all act the same.

B) could it be the cables to the two computers? when operating in 10mbs they are flawless, but 100mbs is hopeless. Is there a wiring configuration that is not friendly to 100mbs?

Additional INFO:
All cables are under 30' in length.
The two faulty looking cables run to drop boxes.
The latest drivers have been installed on the 3Com NICs
The Netgear hub is brand spanking new

 

[DavidDCSA]

If a computer which does not run 100Mb on the vendor-installed line will run 100Mb on your line, then this would imply that the vendor either did not run Cat5 cabling, or they have a faulty installation.