This error can occur on a Mac system for multiple reasons. One reason could be that the OS is complaining that too many files are open. This is a limit that can be adjusted in the OS through the Mac Terminal.(This issue can also be caused by the following: http://avid.force.com/pkb/articles/en_US/error_message/en263503 )
TO CHANGE:
When you get the error in a project close out of Avid Media Composer and open Mac Terminal
Type:
launchctl limit maxfiles 2048 and hit RETURN.
Then go back to the project and see if the errors continue.
Sometimes this number will need to be adjusted up or down. You can try different levels by returning to Terminal and using a different number in the command above.
This will now allow the OS to have 2048 data files open as apposed to the default 256. If you restart the system the setting resets itself.
The following can be performed to have the setting persist between reboots.
Open Terminal and type
sudo su -
You will be prompted for the Admin password for the system. Enter it and hit RETURN.
Type:
echo “limit maxfiles 2048 400000″ > /etc/launchd.conf
*The first number in this example (2048) is the "soft limit" and the second number is the "hard limit". We want to raise the soft limit.