Highlight the RTW icon, right click and select properties. Target should be
something like "C:\Program Files\Rome - Total War\RomeTW.exe" -show_err

If this looks right to you, try making a deliberate mistake in descr_strat.txt - I suggest misspelling a unit name. This will definitely trigger a show_err so you can tell whether it's working or not.

What you describe has happened to me any number of times and as I recall almost always generates a show_err.