On your iMac launch FontBook, Select all the fonts, then on the menu bar go to File > Validate Fonts to be sure you do not have a corrupted font file. Then on the Edit menu run "Look for Enabled Duplicates" and where there are duplicates deactivate the duplicates. Generally that will clear up most font problems.
If we knew what it was we were doing, it wouldn't be called research, would it?
