Saved by SuperDuper, Thanks :)
 

I have a 4 year old Mac Book Pro with the dodgy graphics card...

Yesterday evening the MBP froze. I was able to ssh in to the
rascal and did a reboot.

The system would fail ( gray screen) during the boot.

Fortunately the clone I made the night before would boot, so I
did a smart copy back to the main disk from the backup and within
a few minutes I was able to reboot from the main disk :)

Life is good...

Jerry