This is most commonly due to installing Photoshop CS before doing an archive and install of Mac OS10.3.

The easiest solution is to reinstall Photoshop CS after you have installed Mac OS10.3.
Easiest way to reinstall Photoshop without disturbing the original install is to install to your desktop. after the install is done just trash the Photoshop folder on the desktop.

---------------------------
Another solution courtesy Anne Shelbourne

Open your Previous System folder.
Find "Adobe Unit Types".
Copy it into: <Panther volume>/Library/ScriptingAdditions/ .

---------------------------
Another Addition:

Jim Warthman - 11:31am Aug 15, 04 Pacific (#20 of 21)

This worked for me - but I have one important clarification.

The Adobe Knowledge Base article ( <http://www.adobe.com/support/techdocs/329996.html> ) says to move the "Adobe Unit Types" file to:

[hard disk]/Library/Scripting Additions folder

At least in my case, this did NOT work, until I removed the space between "Scripting" and "Additions". Then it worked fine.

---------------------------
However, if you happen to be running a non-English version, like Photoshop CS CE or Photoshop CS ME, it appears the missing file does not get installed. You would need to install and delete the international English version first.