I found a fix for my new Macbook pro that had these symptoms.
If I booted the laptop while holding down the shift key OSX started and worked normally. If I let go of the shift key the laptop would perform a forced reboot.
I opened up the laptop and disconnected the internal keyboard from the motherboard and everything worked normally. I now use my laptop with an external blue-tooth keyboard as Apple say it will cost £850 to replace the keyboard membrane as a permanent fit.