Thank you MC for your prompt response

I have killed the explorer.exe process from the task manager (taskbar gone) along with every non administrative/essential Windows process while playing a sequence, with no luck.

I am not using a graphics card, just the onboard. A while ago I had some drop-down menu moving very slow on Sonar and consulted this on the Cakewalk forum, to what a senior member there suggested getting a separate video card to fix the issue. I explained to him I did not want to turn my computer into a multimedia environment -as I don't work with video-, or a gamer station since I wanted it to remain a serious audio workstation. My approach from the beginning was to strip down the CPU from things non essential to audio production. However at this point in time I am more than willing to buy a graphics card almost immediately (of any price) if it will solve this issue. If such is the case, please tell me if a simple one should suffice or which one would be recommended.

And to answer your other question no, I don?t use IDE hard disks anymore, I use SATA3gb/s 7200rpm exclusively now (4 of them for distributing sampling loads), as the IDE/PATA driver was somewhat difficult to install properly on my Intel board model under the XP OS.

Firewire chipset?

Do you get DPC spikes when scrolling around in a web browser or playing video files?

Did you test any other audio software (download a trial of Reaper or Live) to see if these also lead to DPC spikes when being used?

Timur I get only ocassional spikes when not performing audio tasks with the FF800 on, as you can see on the second picture.
When opening a task or playing something on Media Player -with the secondary pci audio card- I do not get audible latency problems, but the Latency Checker will still show the advice about some device drivers behaving bad, even with the FF turned off (as in the second picture).
I do have Reaper, Cubase5.1 and some smaller audio apps (none of those yet installed), but I'm already testing with my 2 main apps (Sonar and Audition).

Not sure how to check the chipset, though.

Timur there is no list of graphic card drivers, only one option called ''Intel(R) G33/G31 Express Chipset Family'',  which is the updated driver from the Intel website for this specific board. With the compatible hardware box unchecked I don't get MS drivers, only other Intel models, ATI and NVIDIA ). I'm pretty sure those would not work.
Under Windows7 I had three options for firewire drivers: the normal one, the legacy version and one from Texas Instruments. None of them made the FF work properly. I am now using Vista x64.

I checked again and the Microsoft driver is not called Microsoft but "(Standard...)" at the top of the list.

Once you chose that driver Aero will turn off, as will 3D accelleration. But this is only meant for checking whether the graphic-card driver is the source of the issue anyway.

It should work with the Agere/LSI as well unless there is some problem with the Firewire bus itself. It *did* work for him on XP as he reports and I am using Agere/LSI myself (both rev 6 with repeater before and now rev 7) downto the smallest buffer sizes.

That doesn't mean the onboard FW solution of the mainboard couldn't be the source of the culprit so trying another FW card is a good option.

Sometimes the easy solutions are the best ones. HeadScratch :-)

Already responded to you via e-mail.
If you have further problems, post your detailed specs.

Regards