Sound running slow only in windowed mode

[andreas]

Hi,

does anyone have a clue what's causing this?
I *think* I hadn't this at this extent 1 week before, so what's broken up in my system now?
Apart from that, older WinUAE versions (with some "buts": 0.8.17, too) run fine in my current setup with either windowed or full-screen mode.

Now my windowed mode performance is worse than it ever used to be. Tested with Ottifanten intro from the 'Albedo' version Twist was so kind to put in the zone.
Sound-graphics sync only goes at snails pace, ve-e-e-e-e-r-y-y ch-o-p-p-p-p-y-y-y. One step every half a second. And no, adjusting frame-skip ratio does NOT fix it this time. Sound works a treat when the ottifant stops at some obstacle: when he continues to walk sound goes doing cho-p-p-p-s again.
Full-screen is perfect, though. I don't remember to have installed some new DirectX versions or sort of thing.
I presume that re-installing Windows WILL solve the "problem". But that's what I want to avoid at all costs. I don't have so much time at the moment to spend 3 consecutive days with reinstalling everything from scratch. Blargh. No way.

Notes:
OpenGL OFF
VSync OFF (can't be switched on/off in windowed mode anyway)

Do you have a clue? TIA.

P.S. DO NOT try to use VSync in full-screen mode with this intro. It will make the intro run at insane speed: sound pitch is very high, too.