Use LyX note instead of comment. This is less invasive that
converting Beamer frames to fragile to accommodate the comment
environment.
\end_layout
\begin_layout Frame
-\begin_inset Note Comment
+\begin_inset Note Note
status collapsed
\begin_layout Plain Layout
\end_layout
\begin_layout Frame
-\begin_inset Note Comment
+\begin_inset Note Note
status collapsed
\begin_layout Plain Layout
\end_layout
\begin_layout Frame
-\begin_inset Note Comment
+\begin_inset Note Note
status collapsed
\begin_layout Plain Layout
\end_layout
\begin_layout Frame
-\begin_inset Note Comment
+\begin_inset Note Note
status collapsed
\begin_layout Plain Layout