Inexplicable Sleeping Issues with my MBP (2009)

Upgraded to ML quite some time ago and have had no issues. However, of late, I'm having some difficulties with sleeping - in particular waking.

My MBP seems to sleep just fine most of the time - light goes from constant, noise stops (HDD?), light to pulsating - and will wake upon striking a key.. most of the time.

However, sometimes I will leave the computer - once it is sleeping - for an extended period then return only to hear the HDD / fans on (screen still off, mind you) and I am unable to raise it from its now pseudo sleep.

So far I've tried resetting SMAC and PRAM to no avail. I'm running 10.8.2 and everything seems to be up to date.

Any help would be much appreciated as sometimes I forget to save everything before sleeping and I've already had a couple instances of lost work

Thanks a bunch!
Thom.

Anyone? This be killing me!

border terrier said:

Had similar 'wake from sleep' issue on a Mac Pro and MBP but both solved after PRAM reset. Are you sure the reset worked OK? I seem to recall I had to do it twice on my MBP for it to work and resolve the sleeping issue.

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thanks but i've now tried both PRAM and SMC reset a few times to no avail. after putting the MBP to sleep it will at some point wake up (bar the screen) and effectively freeze.

any ideas, guys?

yeah, it's been done properly. this is beginning to get really annoying. is a clean install of ML going to help? i'm not sure it will considering i can't even figure out what triggered the issue in the first place..