I'm trying to format a document following my organization's style guide. I'm using XeLaTeX for the font flexibility. I made a minimal document
\documentclass{article}
\usepackage{xltxtra} %% For XeTeX font commands
\setmainfont[Ligatures=TeX]{Frutiger LT Std 45 Light}
\usepackage[includeheadfoot, margin = 0.5in]{geometry}
\begin{document}
Main font, no styling, \emph{with emphasis}, \textbf{and bolded}.
\end{document}
and the \emph{} and \textbf{} text comes out just fine, but the rest is garbled:

The part where it's probably my fault
I needed to use this font in some graphs generated in R. I have several fonts in the Frutiger family installed on my (Windows) machine, and they're OTF fonts. To get the font to work in R, I need to use the extrafont package, which only works with TTF fonts. So I fed Frutiger LT Std 45 Light into an online OTF to TTF converter, and reinstalled the TTF version. It works great for my R figures, but maybe that has something to do with my XeTeX font problems. If I run the above example with \setmainfont{Frutiger LT Std 55 Roman} instead of using the TTF-converted light face, nothing is garbled, it's just too heavy.
My compilation report for the example above says 0 Errors, 0 Warnings; the .log file reports
.................................................
. fontspec info: "defining-font"
.
. Font family 'FrutigerLTStd45Light(0)' created for font 'Frutiger LT Std 45
. Light' with options [].
.
. This font family consists of the following shapes:
.
. * 'normal' with NFSS spec.:
. <->"Frutiger LT Std 45 Light/ICU:script=latn;language=DFLT;"
.
. * 'bold' with NFSS spec.:
. <->"Frutiger LT Std 45 Light/B/ICU:script=latn;language=DFLT;"
.
. * 'italic' with NFSS spec.:
. <->"Frutiger LT Std 45 Light/I/ICU:script=latn;language=DFLT;"
.
. * 'bold italic' with NFSS spec.:
. <->"Frutiger LT Std 45 Light/BI/ICU:script=latn;language=DFLT;"
.................................................
Any help/pointers?