Really bad sound and picture lag with 24bit encoded audio movies

I got this very annyoing problem with 2 channel 24 bit 2-pass VBR encoded videos.
I wanted to look at the high resolution movies available @ the official Max Payne 2 website.
The sound was a total mess and you couldn’t hear any sound from the original movie.
Well I started to troubleshoot.
The smaller resolution version of the movie wanted to play without any of those sound problems.

So I took a look at the Audio codecs of the two files:

The Small one:
Windows Media Audio 9
64 kbps, 44 kHz, stereo 2-pass VBR

The Big one:
Windows Media Audio 9 Professional
128 kbps, 48 kHz, 2 channel 24 bit 2-pass VBR

I noticed that the picture was laggy with the high resolution of the movie as well. So I disabled video hardware acceleration in Windows Media Player, didn’t help, picture looks worse but it doesn’t help.
So I thought about disabling audio Hardware acceleration of my soundcard in DX. And: it works without Acceleration.

There are other movies on the website which are also encoded with 24 bit 2-bass VBR but 44 kHz and the problem still persists so the problem must be those 24 bit which my onboard sound doesn’t like mustn’t it?
That’s what Sandra says about my onboard sound:

I took the file to my sister’s computer and it works there without disabling the hardware acceleration :rolleyes:
She has the same software installed and a cheap Elitegroup K7SOM mainboard with onboard sound which shouldn’t support hardware playback of 24bit but it works!

The file plays in PowerDVD like it should, but PowerDVD doesn’t use Hardware Acceleration in Two channel mode I believe.

So can someone tell me what’s the problem here? Bad drivers of my soundcard not managing it correctly to cope with 24bit audio?

And why does the picture get laggy with audio hardware acceleration?

Help is really appreciated!