Bridge Metadata Question

Bridge reports an error writing to file when I try to apply a keyword to an image stored on an EHD. All I can find so far is that this appears to be a Mac problem (no problem for me in Windows). I checked in Finder with Get Info and it tells me I have permission to read and write to the EHD in question. At this point, my Mac knowledge is completely depleted. I don't know what to do next--copying umpteen thousand files to my hard drive in order to apply keywords and then moving them back strikes me as a Herculean task. If I must, I must. But must I?

This isn't a very common problem, and there should be no issues adding keywords to images on an external. What format are the images? It might pay to reset Bridge preferences, or reinstall Bridge entirely. Have you tried applying keywords to an image on your local hard drive? Does this cause an error too? I take it this is Photoshop CS3, and the latest version of Bridge?

It may be uncommon (trust me to have the problem then, lol) but Adobe knows about it and suggests either copying everything to a local disk or making sure that the external has the appropriate permissions. It does work when I copy to the local disk but this is a painful process. I have close to 20,000 images.

I think I do have permission, as far as I can see, so my question is really how can I check to see whether I am the grand poobah of my EHD? Get Info says I can read and write. Do I need an "alter" or "modify" permission? There is no other user except me and I am shown as the Administrator in Accounts.

Thank you for your response, I should have advised it is Photohop CS3 with the latest Bridge and I have an iMac. I am a recent switcher but can't tell you if I had this problem with Windows because I was able to use an amazing Digital Imaging program which can't be run on a Mac. I have tried a few other options but before I fork out more money for yet another program (I am currently running the unsupported and flakey Mediadex) I wanted to make sure that this was truly an obstacle because in nearly all other instances, Bridge is good enough for me. I am strictly a hobbyist.

I did a further test

and pulled a Pages document off the EHD, edited it and then saved it no problem. So, on the basis of that limited experiment, inability to write to the EHD seems restricted to adding Metadata in Bridge. Woe is me.