Invalid model detected

I was editing a model and this error suddenly popped up: An invalid model has been detected. Record the sequence of steps…and contact SketchUp support…
It occurred several times while I was adding text to a solid group and combining them with the union solid tool. The error message pops up for several seconds and then disappears. Afterwards everything seems normal, just wondered if anyone has seen this and if it might be a problem later on.

It’s the font. Either it didn’t install correctly or there’s something wrong with the font file itself.