Scratch

I'm working on a project for a school assembly, and I've transfered the same project back and forth between a school computer and my own several times. When I got it back to my computer, I noticed that some text costumes using a certain font (sf square root) that I have and the other computer doesn't were blank. I tried to edit them, and when I opened the text tool and tried, I got the Red Error Box of Doom. Screenshot below:

and the error box message is as follows:

--Division by 0--

SmallInteger(Object)>>error:
SmallInteger(Integer)>>//
SmallInteger>>//
MultilineStringMorph>>indexForPoint:
MultilineStringMorph>>mouseMove:
PaintCanvas>>textMouseMove:
PaintCanvas>>mouseMove:
HandMorph>>handleMouseMove:
HandMorph>>handleEvent:
HandMorph>>processEvents

I'm going to try and peek at the source code using Jen's instructions. Wish me luck!