Please help, bootcache.playlist error, impossible to boot

Hi all,

My iMac (Intel, Mavericks) freezes during startup,(gray screen with the apple, and the spinning circle).
So, in order to find the origin of this blockage, I booted in "verbose" mode (cmd+v), and I found the following error:

BootCacheControl: could not unlink playlist /var/db/BootCache.playlist: Read-only file system
launch_msg("SetUserEnvironment"): Socket is not connected
launch_msg("SetUserEnvironment"): Socket is not connected
launch_msg(): Socket is not connected

I need expert help because I do not know what to do ...

Is it possible to reset this file ?

I hope someone can help me, thank you..!

Boot from the recovery partition and do a permission repair in Disk Utility.
'Read-only file system' sounds like permissions might be borked on the drive.

I can't do this repair, this option is grayed out..!

You have a most excellent response at the apple forums - work through all of those items one at a time.

I might move item 7 to the top of the list with this error.