I have got a new macbook pro which i have booted up for the first time and did all the basic setup and then restarted it. But now it shuts down automatically when its booting up whilst showing the progress bar at startup half way through.
Please advise how to resolve.
I note that you indicate a Snow Leopard OS which if it is the case, it cannot be a 'new' MBP. I assume that this may be an older MBP that is new to you.
Look at these two articles for possible solutions:
Retrieving data ...