Sound lags and isn't in sync with video in 3DMark03

Strange problem...

XP Pro SP2 (clean install)
Latest ForceWare drivers (77.72) on a PNY 5700LE card, core overclocked by 10MHz (from 250MHz to 260MHz), memory at stock currently.
VSync disabled, and I'm forcing the 1.4 pixel shaders using RivaTweak. No other tweaks applied.

Abit AN7 mobo with latest BIOS, latest motherboard drivers including onboard sound (as a seperate package).

Basically, the problem is this: when running 3DMark03 in demo mode, the sound is almost always behind the video. You can tell because in wings of fury, gunfire sounds are not related at all to gunfire on screen.

Interesting problem, I've got no idea what might be causing it. Anyone got any ideas?

 

Any other apps in the background open that can cause it to slow down?

 

Nah, I made sure minimal things were running, all unnececary services, AV and firewall are disabled too....

 

*bump* nobody got any ideas?