OK so I've reached the conclusion that my Pi is faulty. Below is a list of power supplies that I've tried.
BTW they all power the Pi, but in most cases the Pi crashes, (i.e screen goes blank PWR & OK lights stay lit) after around 2 minutes, the Scosche 4 Port USB works the best I managed to get about 30 minutes use a few times before the Pi shut down. The worse culprits are the Nokia AC-10U Chargers which cause a kernel panic before I even get a login prompt.
I had a lot of these charges/Hubs already, but in the last week did buy a $20 Belkin Kindle Charger and in desperation bought 2 cheap Nokia charges of ebay, so its not surprising they didn't work but I've reached the point where I don't think the power supplies (with the exception of the Nokia's) are at fault anymore.
This is the list of power supplies that I have tried
Scosche 4 port USB Charger QUBSH , 5v @ 2A
Apple iPhone 4S charger A1265, 5v @ 1A
Blackberry Charger PSM04A, 5v @ 750mA
Belkin Kindle charger F5L077, 5v @ 1A
Nokia AC10U charger, 5v @ 1.2A
Dlink 7 Port Hub, DUB-H7, 5v @ 3A
Belkin 4 Port Hub, F5U-404, 5v @ 3A
USB Hub in Dell U3011 Monitor
HP TouchPad Charger, 5v @ 2A - borrowed
Samsung Infuse 4G Android Charger - borrowed
I've also tried Patriot, Sandisk, Wintec, PNY, GSkill, SDCards & used the latest kernel via rpi-update
My Pi was from the initial production run, 2nd batch - 1213.
The only problem with requesting an RMA request is that I have to return it to farnell UK, from USA
Any thoughts ?, or guaranteed to work power supplies I can try! - Need to work in US