It is fixed.
This happens to be a really nasty little problem with Linux and BlitzMax- the system cannot read filenames with capital letters. The script for entering Westwillow calls for the game to load "Westwillow" (notice the capital 'W'). So, this command fails for practically everyone using Linux, but not Mac or Win.
Since this fix involves a change to a map (because the script is embedded in the map file) you will need to wait for the full release of 1.04 to get this proper fix. Furthermore, since previously visited maps are cached in the saved game folder, you will need to either start a new game to see the fix, or you need to reset the map "Ironpool Dam, Lower Level" in your current game if you've already visited this level. I'll post formal instructions on how to do this after 1.04 is available.