I have this problem with two Macbook Pros (2011 & 2012 models).
I've replaced the RAM, battery, harddrive & power supply.
There's no problem with over heating.
I can run the Mac diagnostic screen for hours or boot from the CD.
I went to the Apple Genius bar and was told to replace the logic boards.
It appears to be a boot-no-more switch that's been flipped in the BIOS. has anyone found a way to roll back the BIOS or get around what appears to be built in obsolescence?
Is this a good question?