I'm using LyX on Windows (with Miktex installed) and I'm having problems exporting to PDF. I have successfully exported from LyX to PDF previously, on this computer, with this installation and in fact with a previous version of this file.
When I try to export, I get an error about a missing $ (to the best of my understanding, this means I've messed up the LaTeX code somehow, but I'm not sure how I could have done that since I used strictly the LyX interface (so I blame the program, perhaps irrationally). The attached image shows the error message. The error message confuses me in part because it seems like the compiler has fixed things for me, but then I try to export again and find that things are not fixed.
The offending code (first of several offenses) is as follows: % Preview source code for paragraph 24
\begin{lyxlist}{00.00.0000}
\item [{
\[
\int_{0}^{\infty}Ve^{-\delta t}dt=\left[-\dfrac{V}{\delta}e^{-\delta t}\right]_{t=0}^{t=\infty}=\dfrac{V}{\delta}.
\]
}]~
\end{lyxlist}
In response to: how did I get here? I used the menus Insert -> Math -> Display Formula and then either typed the equation in (using standard keypresses) or pasted in using a cut and paste from an equation originally entered in inline mode. (I can't remember which is true for the offending equations; this is part of a much longer document that has been through multiple rounds of edits.)
\item
. Could you should/explain how you got to this point?