Sorry for the delay. I turned my back on this question due to the constant intervention of an individual, whom I now believe, may have "intellectual issues." I am from the UK and we call a spade, a spade....
The answer is "Sort of, Maybe, NO".
I bought my "Late 2009" iMac in Spring 2010. The installation disks were for Snow Leopard. I subsequently upgraded to Lion and Mountain Lion on-line. So, by the time I had my problem, my system was a mish-mash of Snow Leopard + Updates, Lion + Updates and Mountain Lion + Updates. "A bit of a dogs dinner", as we say on this side of the pond. SHAME ON APPLE for not providing the option for new installation disks when you upgrade.
I had previously got screwed on up something, (can't remember what) and decided to re-install. So I loaded Snow Leopard from CD and upgraded to Lion via Apple Store and later upgraded to Mountain Lion. 'Can't fault Apple Store for remembering what I'd paid for. But what intermediate upgrades did I, should I, have include? I Dunno.
SO, I came to this problem after a Mountain Lion upgrade. I thought that I would reload, again, from SL etc. etc....
'Didn't work. Why? Because the Snow Leopard installation disks were not compatible with the Mountain Lion Installer. This was compounded by having Bluetooth problems which meant that the "cmd" key functions weren't being obeyed. ('Didn't help that, errm, Ham Shanks were going on about the "Option" key, when there is no "Option" key on a UK keyboard.[It's labelled "alt"])
No matter how many times I specified this, I kept being told the same failed procedures. Is there a name for people who give the same advice, thus boosting their help scores and and their egos, making it look as if they know what they are talking about, when they don't?
I shall call them Parasites.
So - What Did I Do? Google is my Friend. I found out how to create a Mountain Lion Bootable Startup Disk. You need an 8GB memory stick, or, as in my case, a Dual Layer DVD (which the iMac will write). Of course, you have to have a valid copy of Mountain Lion from the App site. Once you have paid for software, you are permitted to make a backup copy. You are not permitted to pass your copy to a third party. No, Apple do not tell you how.
I reloaded my system from my bootable DVD, applied ALL the Mountain Lion upgrades INCLUDING the Extra Final (for now) upgrade to 10.8.5 and everything seems to work.
Except for one old email, which I can't get to change it's status from Junk to Not Junk. All the new stuff works OK, though.
My advice, if not too late, is to apply all the updates, including the "Last of the Last (Maybe)". If it still doesn't work, build a bootable ML DVD.
http://www.macworld.com/article/1167857/how_to_make_a_bootable_mountain_lion_ins tall_drive.html
Save what needs saving and try installing "over the top". Then go through all of the ML upgrades, including the "Last of the Last"
If that doesn't work, Install "New" (trash your disks, erase, rebuild and reinstall) then restore. Or, if you haven't got anything that you want to save, just erase and rebuild.
So, "Sort Of, Maybe, No"
Hope this sort of helps.