T61 sound crackling problem during music playback

[zaarath]

Hi there, this is my first post here, so be nice please

I just received a T61 couple days ago and immediately noticed an annoying problem. It makes crackling sound when I play back musi or video (iTune, WMP etc). The crackling is irregular, sometimes 10 seconds after the last one, sometimes 20.

After some testing, I figured that most crackling happens when certain devices make power state switch. Some examples:

cpen/close LCD lid (so LCD powers on and off)
CPU speed change from speedstep
Disable/Enable NIC
Video card enter/wake from power saving state
heavy HDD activity

So if I use max performance or max power saving mode and keep it completely idle while playing back music, the crackling sound rarely occurs.

I've updated to the latest vista sound driver 6.10.1.5370. Just want to know if anyone else experiences similar problem.

My spec

T61 7662CTO
T7300
2GB DDR2-667
80GB 5400 rpm
WXGA+ 1440 x 900
Quadro NVS 140M
Vista Business.

Thanks