if this model has a removable battery.
Boot it from the power adapter only.
Any difference?
Bob, who may be along shortly, always recommends the use of canned air in the vents to clear them out.
Usually gets rid of most of the heat related problems.
I would say a shade late on ordering the external but better late than never. OS X has a good backup system called Time Machine which all Mac users should be using, rather than relying on luck.
Let us know how you get on
P
I have early 2011 macbook , i upgraded to yosemite 6 months ago it has been running fine however the last week it has started being a little slow and now whenever I open garageband or any other programme that requires a bit of CPU the system just crashes and then like the above user on start up it just freezes on a white screen after apple logo.... the only way to combat this is to let the battery drain out and then restart and it will let me back in.... however the same sluggishness and crashing if I open something like garageband remains and then were back to the white screen on restart.
I have ordered an external hard drive so I can back up everything in case it is on its way out.
Any ideas ? Would a fresh reinstall of Yosemite get this back? This was my next step once Ive backed up the files.
I have done disk permission repairs, cleared cache, resest the prag? where you press CMD SHIFT P & R on start up. I have scanned for viruses and malware, cleaned up system and tried to minimize CPU use.
Any other advice would be much appreciated.

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