MBP Booting Issues-Help and Suggestions Please

[SAmigo]

Dear All, (long time reader, first time poster )
I have a late 2006 macbook pro 15" 2.16ghz, every day the computer boots perfectly fine the first time with no issues whatsoever. However if i use the laptop for around more than 30 mins or so and subsequently need to restart the computer for whatever reason or if i shutdown and reboot straight away the computer will not boot. I get the characteristic noise from the DVD drive but not the apple chime and the screen remains turned off.
The only apparent remedy is to leave the computer turned off for a while and come back later.
Any suggestions please-I have tried resetting the PRAM and SMC but not had any joy

Best wishes

 

[Hellhammer]

Is it overheating? You could sleep it instead of shutting down to avoid this issue.

http://guides.macrumors.com/Mac_doesn't_boot

 

[SAmigo]

thanks for the fast reply-it isnt overheating as i just use it mainly for web-browsing and editing these days, it feels cool to the touch and the fans rarely speed up.
I was wondering if the PRAM battery may be dead/dying would that cause the same problem? However the clock time is always correct even if i remove the main laptop battery as well