I had about 1300+ fonts on my system that was causing serious problems, and after getting frustrated with font managers that don't work, I did it manually and dumped most of the fonts to a separate directory. Anyway, it would seem LaTeX is now mad at me.
I'm using the XeTeX backend to allow non-TeX fonts from LyX (checkbox in Document->Settings->Fonts), but I'm actually using tex fonts (from the tex-gyre package - really like these). What's odd is that if I turn off the checkbox, it works, actually using the same fonts! I want the option to use different fonts though, so I want to keep that button on. What did I break? And can anyone suggest a fix - I've tried reinstalling the fonts and fontconfig, and xetex, and none of that helped. What's next?
Here's the error (sorry about the wrapping - thats the way LyX pasted it) ...
! Font EU1/lmr/m/n/10=[lmroman10-regular]:mapping=tex-text at 10.0pt not loadab
le: Metric (TFM) file or installed font not found.
<to be read again>
I wasn't able to read the size data for this font,
so I will ignore the font specification.
[Wizards can fix TFM files using TFtoPL/PLtoTF.]
You might try inserting a different font spec;
e.g., type `I\font<same font id>=<substitute font name>'.