How to approve "Unapproved caller" whilst installing the software? I'm trying to install FUSE for OS X, but it fails with the message:

Unapproved caller.
SecurityAgent may only be invoked by Apple
software.


How do I approve the caller or get rid of that error? What this error actually mean?
It seems it's some kind of temporary glitch, as it usually helps to restart the machine.

Other suggestions:


Reboot into Safe Mode, then Verify and repair drive


Reboot and hold the CMD+R keys
Select Disk Utility
Click on the image under my drive
Verify and repair drive

You may try to remove the cache files/folders located in /var/folders directory (not recommended) or move them into Trash.

Normally cache files should be cleared every few days by Launch Daemon (/System/Library/LaunchDaemons/com.apple.bsd.dirhelper.plist).

If the files can't be removed, reboot into Single Mode, run fsck, mount the root partition and run rm -vR -- /var/folders/*. Which is:


Start on single user mode: Hit the CMD+S keys at start-up
At the line, type (after root): fsck -fy and hit the Enter key.
Mount the root drive by: mount -uw /
Remove the cache files by: rm -Rf /var/folders/* (make sure you won't do any typo!).
Reboot by typing: reboot.