I belive the maximum CAT5 segment length is 100meters. About 330 feet. So yours should be okay.
I would check the ends closely, or have someone clamp new ends on. Make sure all the wires are tight in and that you can see the coper cores right against the front of the plug. In other words, inspects the wires inside the plug and make sure none are pulled back and not pushed all the way into the plug.
Check all along the cable, make sure it is not runing along any high power devices, generators, halogen lights, power lines etc... Which cause a lot of crosstalk and screwing up your signal.
Then try a different port on the router, just in case. Try a new network card in the warehouse machine.
Lastly, you said the computer is over 200 feet away, but how long is the cable itself? IF it's 250 or 300+ then it's possible you have cable length issues.
You could go and get some CAT6 cable or CAT5e, which may have longer segment lengths. Or you could put a switch somewhere in the middle.
It's actually a bit difficult to find a good document about the various types of cable and their lengths etc... I couldn't find a good one for the ten minutes or so I looked.