this is a  long shot, do you know where to find your Main FSX.cfg file?

if not type this into your start bar search box

%AppData%\Microsoft\FSX\fsx.cfg

make a backup first incase of a FUBAR.

open the file with notepad ONLY

look about half way down the page  for the following section

[Trusted]

and search for the Captain_sim 737 entries and delete them.

save the fsx.cfg file

re run fsx and load the 737 it should ask you to accept the .dll files and gauges again.

Bruce