Do you have ignore Permission checked on the external drive?
Are any of the files/folders being copied from another user?
Old -50 info...
Also, incompatible characters in a name can cause this error.
Thanks for the help BDAqua,
After the first time the issue occurred I did try to check the box "Ignore ownership on this volume", but that did not fix the problem. (Should I leave it checked or unchecked in this case?)
As far as other users files and incompatible charachters, I don't believe this is the case, since it gives me the error even if I just try creating a new folder on the drive.
I did see that old -50 info before posting my question, but I didn't think that it quite fit my issue since my issue isn't limited to copying, and that problem seems to be when copying from a remote disk to the startup disk.
Any other thoughts?
Thanks again for your assistance.
I think the old info was incomplete & just mentioned the first instance/cure, I think it works both ways.
Leave it checked I think.
#1. Safe Boot from the HD, (holding Shift key down at bootup), run Disk Utility in Applications>Utilities, then highlight your drive, click on Repair Permissions, when done trash this file, then reboot & try it...
#2, In System Preferences>Accounts, unlock the lock, click the little + icon & add a new Admin user, log into that account & see if it works.
#1 - Disk Utility won't let me verify or repair disk permissions on any of the external drives (The button is grayed out) I was under the impression that the OSX tools for disk permissions only pertained to the system drive.
#2 - isn't really an option for me. I'm using this mac mini as a webserver and there is a lot tied into the main admin user.
Any other ideas?
What I find the most odd is that after re-boot or re-mount it works fine, and then after some not set period of time it stops allowing me to write to it....