Odd vsync problem

[Lusche]

As recommended, I always fly with Vsync enabled and thus the FR shown in game tops at 60.

Now tonight I was playing around with ther self shadow size during a boring sortie. When I raised the shadow texture from 2048 to 4096, I suddenly saw the FR counter jumping up to values way above 60 and staying there. When I ended the sortie and went to the initial video configuration screen I saw that vsync was still being enabled (box not checked).
But no matter if i checked, unchecked and/or restarted the game, vsync stays effectively disabled in game, FR is way above 60 (no, vido8.cfg is not read-only)
Now the really odd thing: enforcing vsync DOES work on the initial start screen (I checked with fraps), it just stopped to work in game, both off- as well as online 

i3-2120, win XP prof
AMD Radeon HD 6850 /1GB
Driver Name: ati2dvag.dll
Driver Version: 6.14.0010.7256 (English)
only basic drivers, no catalyst control center or similar stuff...

[FLS]

I have a similar issue with an Ati 5970. FPS is capped at 60 on the start screen with vsync on but it's capped at 120 in game. With vsynch off it's much higher in both cases so vsynch is doing something. Vsynch is on in AH and Catalyst 12.1. I don't notice any problems from it in game.

[FLS]

Fixed this by installing an older driver 10.10.

[Lusche]

While I had rebooted my windows and it persisted, it went away after shutting down the computer completely. I tried to recreate the bug, but this time meddling with shadow texture size had no consequences.
In all cases I haven't tweaked any graphics or driver settings outside or in-/deinstalled any software, so for now I guess it's just some driver glitch.