Hard drive storage not adding up, lots of other and close to full, seems to be increasing on its own.

Question

I was shocked to see that my hard drive was close to full last night when I checked on its capacity.  Mainly because I just wiped clean a month ago and reinstalled with the current version of Mavericks.   It would appear that my problem lies within a massive amount of storage used classified as "other".  My HD holds 320 GB and of that, "other" is taking up 161 GB along with my Audio, Movies, Photos and Apps taking up a combined 120 GB.  This leaves me with about 40 GB left of free space.
I am unable to pinpoint the location of these "other" files.  Totaling up the four subfolders in my HD (System, Library, Users and Applications) only amounts to 120 GB which can be traced back to my Audio, Movies, Photos and Apps.  This leaves 161 GB floating around used somewhere that I haven't the slightest clue of where it is.  I have used Grand Perspective and a disk space analyzer from the app store and they both only recognize 120 GB being used by the hard drive.
To make things a little more interesting, when I first noticed this "other" issue, it was taking up 145 GB and over the course of an hour or so after multiple restarts it has worked its way up to the 161 GB it is at now.  Is there some type of glitch here?
I have tried restarting in Safe Mode to reset any stuck processes, but that didn't work either.  I have searched similar problems but most people have found massive log files which they were able to pinpoint using a disk analyzer. 
With a clean wipe and reset only a month ago, how can the "other" be this big already?  Any ideas?  Any input is greatly appreciated, Thank you!
I have a 2007 iMac which ran great with snow leopard...I currently have the latest version of Mavericks 10.9.4

Answer 1

For information about the Other category in the Storage display, see this support article. If the Storage display seems to be inaccurate, try rebuilding the Spotlight index.
Empty the Trash if you haven't already done so. If you use iPhoto, empty its internal Trash first:
          iPhoto ▹ Empty Trash
Do the same in other applications, such as Aperture, that have an internal Trash feature. Then restart the computer. That will temporarily free up some space.
According to Apple documentation, you need at least 9 GB of available space on the startup volume (as shown in the Finder Info window) for normal operation—not the mythical 10%, 15%, or any other percentage. You also need enough space left over to allow for growth of the data. There is little or no performance advantage to having more available space than the minimum Apple recommends. Available storage space that you'll never use is wasted space.
See this support article for some simple ways to free up storage space.
You can more effectively use a tool such as OmniDiskSweeper (ODS) or GrandPerspective (GP) to explore the volume and find out what's taking up the space. You can also delete files with it, but don't do that unless you're sure that you know what you're deleting and that all data is safely backed up. That means you have multiple backups, not just one. Note that ODS only works with OS X 10.8 or later. If you're running an older OS version, use GP.
Deleting files inside an iPhoto or Aperture library will corrupt the library. Any changes to a photo library must be made from within the application that created it. The same goes for Mail files.
Proceed further only if the problem isn't solved by the above steps.
ODS or GP can't see the whole filesystem when you run it just by double-clicking; it only sees files that you have permission to read. To see everything, you have to run it as root.
Back up all data now.
If you have more than one user account, make sure you're logged in as an administrator. The administrator account is the one that was created automatically when you first set up the computer.
Install the app you downloaded in the Applications folder as usual. Quit it if it's running.
Triple-click anywhere in the corresponding line of text below on this page to select it, then copy the selected text to the Clipboard by pressing the key combination command-C:
sudo /Applications/OmniDiskSweeper.app/Contents/MacOS/OmniDiskSweeper
sudo /Applications/GrandPerspective.app/Contents/MacOS/GrandPerspective
Launch the built-in Terminal application in any of the following ways:
☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)
☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.
☞ Open LaunchPad. Click Utilities, then Terminal in the icon grid.
Paste into the Terminal window by pressing command-V. You'll be prompted for your login password, which won't be displayed when you type it. Type carefully and then press return. You may get a one-time warning to be careful. If you see a message that your username "is not in the sudoers file," then you're not logged in as an administrator. Ignore any other messages that appear in the Terminal window.
The application window will open, eventually showing all files in all folders, sorted by size. It may take a few minutes for the app to finish scanning.
I don't recommend that you make a habit of doing this. Don't delete anything as root. If something needs to be deleted, make sure you know what it is and how it got there, and then delete it by other, safer, means. When in doubt, leave it alone or ask for guidance.
When you're done with the app, quit it and also quit Terminal.