Last night, I was goofing off the IFSD Scenery and taking a flight in the PSS Concorde. I noticed the following problem:
It took me a while to find the solution on the web, so I am posting it here, with the fix. Basically, some other add-on that I have installed in the past month (still to find out which one) played around with one or two of the effects files.
To fix, download this zip file and replace the incorrect FX Files. Backup the originals, just in case! (Thanks to Neil Davey for the replacement files)