Error Saving Mpc Project

Hello
New renaissance user coming from 10+ years on a 2000xl, loving everything about the new gear, the workflow is familiar and easy to adjust to. I'm still just skimming the surface but I can tell the soft wares a beast.

Anyways I'm having trouble "saving project as" directly onto my external HD, "error saving mpc project". I can save to default user/documents/mpc no problem. Few days ago I loaded the external HD with sounds and projects from a buddies studio on it with his iMac desktop and can load those up at my house with no problem using my MacBook Pro. I just can't seem to save anything on the external HD using my MacBook Pro. Doesn't let me create new folder either.

I'm currently running mpc 1.7 software everything's up to date. Brand new 2012 MacBook Pro 2.5ghz 16 ram,
Seagate 3Tb HD.

Not sure if this is mpc software related or it's an issue with the macbook/seagateHD
I even tried plugging the HD directly into the Ren with no avail. I've tried saving directly to default mpc documents, which functions properly, then dragging into the external HD but no good either.
This is very frustrating. Anyone with any insight would be highly appreciated, thanks.

First thing to check:

Make sure the drive is not pre-formatted for windows pc's (NTFS). Mac OS can view these files however, cannot write to disk (which essentially also means create folders).

If indeed that is the case, you can purchase 3rd party drivers to remedy or backup to another disk. Then reformat the HD to Mac OS Extended or (journaled) format, then re-copy the files back to it.

Let us know!