Bingo, Simon. Thanks.
Running Validate Font on all my fonts on my iMac did indeed result in
"Warnings and Errors" that there were duplicates -- including key 'default'
fonts like Arial and Palatino.
Some of those fonts were in:
~/Library/Fonts/
Duplicates were in:
/Users/*username*/Library/Font
David,
that is typically a sign of damaged fonts in your system. Open the Font Book
(in Applications), select User and see if there are any broken fonts and remove
them. You can also select fonts and run File -> Validate Font. Either way, you
can compare your font configuration on both machines
