Thanks folks, well I booted into Windows on my Mac and finally managed to reload the present 1.2 OS via NSU. Unfortunately the boot problem remains! ie, "when I put a newly charged battery in my N900 it immediately vibrates and tries to boot (ie. before pressing the start button)! Then it won't boot but instead cycles through a bootup process never quite booting!"

Further to the boot problem, recently I have noted extremely short battery life, I'm talking only an hour or so and sometimes even less (I rotate batteries with one always on charge). Perhaps this is due to the repeating bootup cycle required to startup the N900?

I am yet to try the R&D mode flash suggested by sepehrsfmech above. I'm not so familiar with the terminal so I want to be sure how this is done before I try.

Any other ideas? Thanks.