I've installed Mathcad 11 - And all went just fine :)
The problem occured when writing functions, symbols like + - * was just shown by a square ([]).
The solution for me, was to copy the file "symbol.ttf" from Windows/Fonts/ to ~.cxoffice/bottle/drive_c/windows/fonts/.
You need to get the file from a Windows installation :)
Felt like I had to share this information .
- Anders