You have to reclaim ownership of the drive.  Files made on one computer's hard drive and then accessed by another computer will have different ownerships.

Below is the guts of the issue for a Win7 machine for permission problems with Bridge. Concept should be same for you.   Hope it helps.

1. First make sure that you have Administrator rights on your system via the Control Panel
   
   
2. Next ‘right click’ on the Drive whose files you want to gain full access to, for example the drive that your pictures are stored on, and click on 'Properties'.
   
   
3. Under the Security tab you will see a list of Groups and Users on this drive and the Permissions that they have to do things.
4. Before doing anything to edit these Permissions, first click on the Advanced button. This opens another window with a tab showing the Owner of this drive.
    
   
5. Click on the Owner tab and if you are not already listed as the owner, make yourself the owner by selecting your name from the list. I believe it should appear there if you are an admistrator or user. (In my case at this stage the owner was initially shown as an obscure string of numbers and letters which I believe identified the drive when it was connected to the lap top I was using before I upgraded my machine)
   
   
6. Now be sure to check the box that says "Replace Owner on Subcontainers and Objects" and the click Apply. On completion of this step, the drive in question and all the folders, subfolders and files thereon should now be 'owned' by you. You could check this out by right clicking on a particular folder then clicking Properties > Security > Advanced > Owner. Your name should appear. So far so simples!
   
   
7. Now go back to the Security Tab for your drive (Step 2 / 3 above) and look at the Permissions you currently have. Your aim now is to allow yourself 'Full Control.' If you don’t currently have this level of permission click Edit, select your name on the list, check ‘Full Control’ and 'Apply' the change.
   
   
8. I think I'm right in saying that at this point whilst still working in the Drive directory you are now given the option of ticking boxes which allow you to, in effect, cascade the permission you have just granted yourself to all the files and folders on that drive. Tick the box to allow this and Windows should then take care of the rest.If I'm not quite correct here then in my particular case, for example, all my images were stored on my external drive. The top level, or 'parent' folder in which all my pictures could be found was the 'My Pictures' folder and I had created a number of folders and subfolders ('child ' folders) within that folder. The permissions I gave to the Parent folder – My Pictures – were cascaded down through the Child folders.

Well rats.  But ths same concept applies,  now you just have to figue out where to look.

Try the web - hard drive ownership mac computer.