Like I said, I think this is a drive permissions issue. Make sure the session isn't on the main Mac HD.
The first thing I'd do is copy the session to another drive and try and open it that way.
Then if I can get the session open, check my disk allocations and permissions for the session and make sure none of them are set to the main HD.
If that doesn't work, check both your Audio Files and Fade Files folders for files with potentially illegal characters like !@#$%^&*(){}|<>?:" etc.
I'd also trash your pro tools preferences files and if it still doesn't open, trash the preference files again and repeat the steps above.
Here's a list of Troubleshooting tips from Avid:
Delete Pro Tools preferences.
-Go to Users > “your user name” > Library > Preferences
-Delete 'com.digidesign.protoolsLE.plist', 'DAE Prefs' (folder), 'DigiSetup.OSX' and 'Pro Tools preferences'.
-Empty trash, then restart the computer.
You can also use the Pro Tools Preference and Database Helper to trash preferences and databases automatically, as well as providing a few other useful tools. (This application is provided by a 3rd party and is not tested or supported by Digidesign)
Repair Permissions
-Quit Pro Tools and launch Apple's "Disk Utility" application, located in:
MacHD>Applications & Utilities.
-Select your boot drive (the whole drive, not the volume underneath the drive)
-Go to the 'First Aid' tab and select "Repair Disk Permissions"
Apple recommends doing this any time you install new software, update your OS or install any software.
Delete Databases and Volumes
This step can be useful when receiving random 'assertion' or 'neoaccess' errors, especially when recording or saving.
-Delete the "Digidesign Databases" folders on the first level of all mounted hard drives.
-Delete the "Volumes" folder:
Pro Tools versions 7.3 and earlier it's located in MacHD > Library > Application Support > Digidesign > Databases.
Pro Tools 7.4 and higher will find it in MacHD > Library > Application Support > Digidesign > Databases > Unicode.
-Empty trash, then restart the computer.