Win7 "Not Responding" freezes on every software

I have a Dell Precision M6400 whose hang behavior has absolutely stumped both myself and Dell ProSupport (we are both still working on it). It engages in a rhythmic freeze-type behavior that bears some functional resemblance to thrashing, except that it's not being anywhere near over-taxed. Sometimes the freezes terminate in "Not Responding" messages and crashes, and sometimes it recovers. It's not unusual for it to spend one-third to two-thirds of its operating time frozen, which makes it unusable. During freeze intervals, it won't even accept keystrokes. Procmon records those intervals as being empty of log-able events, and CPU activity falls to 0%. Individual hangs generally last three to ten seconds.

Dell has thus far replaced much of the guts under warranty including motherboard and processor, with no improvement. A fresh Win7 install today did not help either.

I have seventeen videos of this behavior posted thus far to YouTube under the username EnviroSteele. There have been other bizarre behaviors besides the hangs and some of those are shown in the vids, but mostly the issue is freezes/hangs/thrashing?/Not Responding.

Any ideas that you folks could give me would be very, very, *VERY* much appreciated. Thanks.