Mountain Lyon 10.8.5 Apple Apps Crashes

I have had Mountain Lion installed since the day it was released. Recently however, I have been experiencing a lot of lockups or crashes of some internal Apple apps such as, Finder & Preview, so let's focus on those two.

Randomly for no apparent reason find or will just stop functioning it does not respond to reload and I ultimately have to hit the power button kill the machine and restart it. In the ideas of what might be causing that?

Are you just preview quite a bit to make simple editing changes to photographs primarily JPEG's. It seems to crash frequently after making changes to say the color adjustment or crop or a size adjustment. It seems to help if I save the edit right after I do it at each step. Then other times, like this morning, it just crashed no matter what I did.

I have not upgraded to Mavericks OS X yet because there are couple of third-party programs that are not proven to work with Maverick just yet. Up until maybe three months ago I had no issues of these lockups and crashes of internal Apple applications using Mountain Lion.

If it's important to know this is what I'm running Mountain lion on;

iMac 21 1/2 inch late 2009

Intel Core 2 Dual processor at 3.06 GHz, 8 GB of RAM and a 1 TB internal hard drive.

Operationally, I rarely exceed 50% memory usage and my hard drive is standing at 51% used. The oddest thing is that I'm not having any issue with third-party apps Adobe, Microsoft and various other third-party vendors.

Short of doing recent reinstall of mountain lion, I'm not sure what I can do is anyone have any idea what might be causing this?

Wayne