Thanks for your help, Tom. I have been carefully going over the steps I have tried so far.
During boot, holding down shift to run in safe mode - Mac powers off after chime.
" , hold down C with Install/restore disc in, - Mac powers down after chime.
" , hold Cmd and S - Mac runs up to terminal-style screen of text ending with a localhost:/ prompt.
not familiar with Unix terminal cmds - but I am boning up. (see later).
During boot, hold down Cmd, Mac runs up in c 20 seconds to screen visible showing rest of software loading to give nornmal desktop. The published function of Cmd during boot is to disable Virtual Memory.
BTW I have noticed a strange occurrence in that when I click on "detect displays" the "Cancel, Sleep, Restart, Shut-down" dialogue box appears???? Just in case that is somehow being invoked during boot up, I have tried booting up with regular pulses of the Esc key (=cancel) until the screen become visible - and it works!
After mulling over with a colleague & a beer, I am going to start using Unix commands in Terminal to look for the Virtual Memory paged files on the disk, which I believe may hold data stored during turning off that is designed to restore the working conditions after recovery from sleep/shutdown.
If some of this data is corrupted, and it is read during boot-up after the chime, it could be invoking the Cancel, Sleep, Restart, Shutdown dialogue (still invisible becaiuse the screen is not up yet) with a short time delay before the default (Shutdown) is executed.
Hence pulsing Esc key during boot which would cancel this dialogue box before Shutdown executes??
Now I need to study Unix commands to ensure I only do passive actions like list files and change directory before I think of moving or deleting files perhaps in due course.
Perhaps it would be better to use Cmd + S to access the Unix commands, so that no other software is running when I explore with the files on disk? Is this what it's for?
Regards
Peter
