Getting nuts and losing time / pops & cracks

Guys I am getting nuts with this : Mixing under Vista 64 bit is totally impossible without recording pops and cracks in the final mixdown track. It's random at every trial. Never the same place. Sometimes it won't hear on the final track at playback. Sometimes it will. I've lost hours and hours trying to get a clue out of this.

I have no problem at all on this very same PC (dual-boot) when I work under XP 32 bit. Unfortynately, I have worked projects in Vista 64 bit on that PC and since the Dakota card WDM drivers work very badly under 64bit, I have to use ASIO drivers in Vista, while I use WDM under XP - so kind of hard (because of different mappings) to go back in XP once an entire project had been worked in Vista.

I have tried to increase i/o buffer by 128 increments, and up to 2048 !.... Still the same. Unchecked the 64bit double precision engine. Switched full chase lock to Trigger and Freewheel. Switched (under GLOBAL settings / Audio Data) the 'render bit rate' to 24 instead of 32 bit. Nothing seems to work. I'd like to run the WAVE PROFILER, but where do the hell has it gone under 64bit program ? (Or maybe it is not there because I run ASIO drivers ? - I can see it clearly under XP).

I almost *never* experienced this problem with the 32 bit version - and since CPA 9 !... Just under Vista 64 bit.

Ideas ? Solutions I may not have thought of ? Encouraging words so I won't depress ? I thought of upgrading to S8, thinking maybe the 64bit implementation could have improved, but I read many of you have worst problems so I'll wait.... And Cakewalk so not seem to shake the bells and whistle about the 64bit systems like it used to do 2 years ago...

Thanks,
Rob

SETUP is the same under both OS :

Core 2 Duo 1.86
Vista 64 bit Home Premium
4 GB RAM
SATA 2 HDD
SONAR PRODUCER 6 with all updates installed
Frontier Design DAKOTA lightpipe ADAT to Yamaha 02R version 2 mixing board (external)