ZEPHADUS'S PROFILE

Hey guys, I'm new obviously.
I'm not usually the type to ask for help, as I usually find the answers after digging around long enough, but I've been at it for hours now, with no results, so...

Does anyone know how to change the row height (vertical space) between lines of text in message boxes?
I'm trying to use a different font (MS Sans Serif) at a smaller size (somewhere between 16-20 oughtta do), but when I do that, I get an enormous gap between lines.

I am using DubeAlex's Advanced Message Script, but I could just as easily not, if that helps fix my issue.

Anyone able to shed some light on this?