There was a bug in the titling when MS3 was first released. I don't remember it affecting font selection, but it would be worth checking you've got the most recent release.
Did you just now upgrade to 3.0? Version 4 has been out for a month or more. You might be entitled to a free upgrade to 4, since at this point in time any upgrades from version 2 should have been to version 4 instead of 3. Check with customer support to see if they can arrange that for you.
The "bug" was scrolling credits - it evidenced itself by not being able to edit a previously created credit. I do not recall it being font specific. Definitely download any upgrades to version 3, or upgrade to 4 as was already suggested.