A reinstall is not necessary, I went through the same deal this morning.
If you performed an archive-and-install with Tiger [the cause of my dilemma], you need to do the following:
1. Go through the "Previous System" folder on your drive, and inside Library, there's a folder called ScriptingAdditions.
2.Take the Adobe Unit Types file from in there, and...
3. ...Move it to a folder of the same name [ScriptingAdditions] in [either] the library folder in your "System" or just the Library at root [the one that pops up alongside Applications/Desktop/Users.
I can't recall, now, which spot it needs to be dropped in, I tried both.
Drag-and-Drop into apps in the dock [Photoshop, particularly] works for me once again.