If the laptop keyboard was replaced and the external works, then the outlook is grim (expensive) since the only other parts that could be defective are on the motherboard.
But one needs to find out if it's the OS or not. If this was mine, I'd boot a KNOPPIX CD for a test run. Here's the articla about it.
http://tips.oncomputers.info/archives2004/0401/2004-Jan-11.htm
Even a DOS boot could figure this out. But you need to find a test without using the OS on the hard disk to get a direction of what to do next.
Read http://www.doxdesk.com/parasite/ and be sure there are no pests in the machine as well.
Bob
After waiting 2weeks for a new keyboard..mine still isn't working correctly. The problem is I have to type the letters 2+ times for them to register. I have tested with an external keyboard and it works fine. Any suggestions? It takes forever to type anythng readable due to this problem.

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