Just found this thread and wanted to share that I'm using a Lenovo Thinkpad T420 with Windows 7 professional. My driver version is 12.10.29.0 and I'm having the same issue. DPC latency checker shows a spike every 4th tick that is around 6100 us. It is causing issues with pro audio recording.
If I unplug the ethernet cable or disable the driver in device manager, the spikes go away.
Any help would be appreciated. Sean