Something is strange here. That screen says your drive has a formatted capacity of 75 GB and you have 65 remaining. There's no way that disk is too full. That is your boot drive, right? It's the only one shown.
Can you try this? In the First Aid tab of Disk Utility, on the bottom right side is an option, "Verify Disk" (not "Verify Disk Permissions"). Run this. The computer may be non-responsive for several minutes. At the end, it should give you a report like this:
Code:
Verifying volume Macintosh HD
Checking HFS Plus volume.
Checking Extents Overflow file.
Checking Catalog file.
Checking multi-linked files.
Checking Catalog hierarchy.
%)
Checking Extended Attributes file.
Checking volume bitmap.
Checking volume information.
The volume Macintosh HD appears to be OK.
Mounting Disk
1 HFS volume checked
[COLOR="Green"]Volume passed verification[/COLOR]
If it does not have that last line in green, then you have a file structure issue, and you should do the following:
After saving files and closing applications, insert the install DVD for your operating system into the drive, open system preferences, go to startup disk, select it, and then click the restart button in the window.
The computer will boot off the install disk -- do NOT re-install the operating system. If you go to the options or maybe the menus at the top of the screen, you will also get an option to do things like repair the disk. Do this, and in Disk Utility, an option called "Repair Disk" (not Repair Permissions) will now be available on the right side of the First Aid tab. Usually, this option is greyed.. Do this. It should look and see if something is wrong with your disk file structure and fix it.