Let me just contribute to the general confusion about this:

I couldn't see any reflections in the water the first couple of days I used
FS04 - no matter how I set the sliders. Then I scanned a local (danish)
newsgroup.

One guy wrote, that in order to really see the water reflections, you had to
go to "international settings" and change it from "Danish" to "English
(US)".

This sounded as the most far out thing I had ever heard - but I tried it -
and it worked! Now I have really cool reflections and it really doesn't
affect framerate much!

Only thing that really confuses me now is that I used to get the best
fraerates in fullscreen mode. Now, I get rates of 20-25 fps in Windows
mode - but only 10-15 fps in fullscreen. (resolution: 1280x1024 in both
views.

Thanks for that Anders, as to why it happens I can't help, can you
please let me know about your video card and drivers so I am sure to
have an example when reporting it?

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Best
Katy Pluta

FS2004 FAQ at http://www.simflight.com/news5/modules.php?name=FAQ