Currently Being ModeratedDec 14, 2012 4:47 AM (in response to Clive P.)
Is the machine 4 or more years old? The PRAM battery may need replacing.
Currently Being ModeratedDec 17, 2012 2:14 AM (in response to a brody)
Thanks for the reply but I changed the PRAM battery and first thing this morning the problem returned.
Currently Being ModeratedDec 17, 2012 2:37 AM (in response to Clive P.)
The only thing I can think is that a firmware update didn't apply correctly. Bring it in for service.
Currently Being ModeratedDec 17, 2012 7:49 AM (in response to a brody)
Can I reinstall Lion without wiping my drive? or use my time machine back ups to go back to before the problem?
Currently Being ModeratedDec 17, 2012 8:28 AM (in response to Clive P.)
I don't think that will solve the problem. A corrupted firmware is difficult to remove from the logicboard, short of replacing the logicboard. Though perhaps the Apple Genius bar may have some open firmware tricks up their sleeve.
Currently Being ModeratedDec 29, 2012 10:24 AM (in response to Clive P.)
Boot off your *original* Install Disk while holding down the *d key*, (not c key), then run the extended Apple Hardware Test. Some disks require you to use the Option key at bootup to select AHT. Some Discs have it inexplicably on Disc #2. Some models have a separate AHT CD.
The Memory test can really only be trusted if it finds a problem, not if it doesn't find a problem.
Memtest OS X...
Rember is a freeware GUI for the memtest ...
Have you blown the dust out lately?
Get Temperature Monitor to see if it's heat related...
And/or iStat Pro...