Windows 7: Major DPC latency issues

Hi,

I've been having DPC issues on my desktop for many months now. Recently, my HDD crashed and after replacing it, the DPC issues stopped for a while, but now they're back and it's clearly not my HDD that's the culprit.

It seems to happen most (but not only) when I play the game Vindictus. The normal system stuttering occurs and if I exit the game, it still continues. The DPC latency checker will basically show all red bars.

I have installed and run xperf when my system was running fine and on my latest DPC attack. Looking at the summary table of DPC CPU usage in xperfview, these are the top modules and their max actual durations during the xperf trace:

EagleX64.sys - 265ns
HDAudBus.sys - 108ns
ndis.sys - 90ns
ntoskrnl.exe - 32ns
USBPORT.SYS - 32 ns



I should also note that sometimes, but no often, when my PC is having DPC problems, I'll get a notice in the bottom right that says something about my USB ports are not connected, or something along those lines.

My specs:

Windows 7 Professional
Core i7 920
ASUS P6T mobo
Integrated RealTek audio on mobo (I have a suspicion it might be this thing, as most RealTek drivers suck)
GeForce GTX285

A while ago, during one of my DPC attacks, I tried disabling various hardware in Device Manager, but was unable to find the culprit. This is really driving me nuts...