high dpc latency 3.8 seconds! ataport.sys intermittent a/v buzz/freeze

Microsoft drivers are running the onboard hd audio, the realtek drivers don't seem to load; i've downloaded some updates for this jurassic MB from asus for windows 7 and they can't find the hd audio device [that's present and working] so they won't install. i've also downloaded some updated drivers from realtek but haven't tried rebooting installing one of those yet.
the issue: intermittently the screen will freeze for just about 4 seconds, if there's audio playing there will be loud buzzing like a 120Hz leak through a bad PSU. This will happen regardless of what apps are running. There are no programs crashing, no bsod's and after the timeout everything still works ok.
Using Thesycon's dpc latency checker the spike tops the scale at the time of the event. Using resplendence latency monitor 3.0 I can see 3,800,000 microsecond delays attributed to ataport.sys. The IDE drivers running the sata and atapi are also all microsoft's since asus has no updates for the ide controller. nvidia's chipset update 1554 seems to have updated some things but I have to reboot to see if it's had any effect. There'w an ide folder in that update but when running setup there's no sata/ide install option, and there's no other way to install it.
The video is onboard geforce and though this is showing an nvidia driver there's no control panel available-this is not a concern.
If I peruse device manager I seem to have duplicate instances of several devices:
under ide ata/atapi controllers I have two instances of ata channel 0, two of ata channel 1 and two of standard dual pci ide controller.
The monitor is listed as generic but it works fine so I haven't installed the OEM AOC software.
Under sound/video/game controllers there WERE two instances of high definition audio device, but since the realtek update one now says realtek; i don't know if it will stay like this untill i reboot.
my brain hurts.
I've imaged the system so I can always get back to square one and try again.
Here's a new record: latency monitor now shows an isr execution time of 17,006,397,785,633 microseconds and dpc time of 17,028,594,909,264 microseconds after a seven minute run before it got caught in a floating point error message loop--i'll upload the report. i don't trust this prog 100% since it reports my 2.7Ghz cpu's running at 3.549GHz [if only it could...] and that I shoud disable wireless adapters that don't exist.
I've got a torch, saws, a few hammers and axes and a mig welder: what should I do next?
jeff

but the latency issue still persists.
where's that hammer...

anyone have a clue?

sorry for the late reply, and thanks for yours-I gave up and reinstalled windows 7. Here's the report from latency monitor, it seems to flag ataport.sys as the cause. I can;t seem to find any updates for this, and all versions of software for the ide and sata controls in the chipset don't differ [the one installed with windows 7 and several versions from nvidia]. It also thinks my pcu is running at 3.4GHz but that may be a glitch.
Perhaps a clue exists which points to a basic hardware issue? Hmmm...
Right now the pc is using a copy [real legit official yadda yadda] of windows xp pro and the bios settings have all been switched back to 'auto' and that freaky 5 second freeze persists. All the drivers are updated as is the OS. DPC latency checker says " Some device drivers on this machine behave bad and will probably cause drop-outs in real-time audio and/or video streams. To isolate the misbehaving driver use Device Manager and disable/re-enable various devices, one at a time. Try network and W-LAN adapters, modems, internal sound devices, USB host controllers, etc." Peak latency after just a few minutes of running IE are 760ms; earlier today it was 1.5s after running a few hours.
I'm stumped.
jeff

Still intermittent; happens with xp pro and 7 in all stages of updates/service packs and with all versions of device drivers. Logically this is a hardware issue; does anyone have a clue?

so i guess you don't have a clue.

I have the same problem, and have found multiple unresolved instances of it discussed on the web.

Somebody needs to figure this out and get the word out.