Ok my first post so thanks to anyone that helps out.
I used to run a cable modem --> computer/server --> hub --> 2 other computers. Worked perfect!! OK NOW Im sick of the server been occupied by someone and they unintentially shut it down.
So i have purchased a Router/4 port switch for the cable internet lan to stop this problem. Lan is as cable modem --> Router --> 2 computers. I set it up today and did a dummy of how it was goin to work with one computer. The cable was short less then 5 Meters. Worked fine, and now i went to do it with long cables and it doesnt work, but the same computer with a shorter cable its works perfect. Im using a straight through (colour arrangement is o/w-o-g/w-blue-blue/w-g-brown/w-brown). What is wrong ???

Your longer cable may be miswired.

pairs don't look correct
see here:
http://www.netspec.com/helpdesk/wiredoc.html

Ethernet is good for ~150' and then you need a switch or hub to "rebroadcast" the signal, otherwise it gets too weak. As suggested above, check your wire pairs again and make sure they are firmly seated, bare-metal to bare-metal & w/o shorts between the ends. Sometimes the cable itself is bad with shorts in the lines between the connector.