BSOD every 30 minutes (clfs.sys / irql_not_less_or_equal)

So my Win Pro X64 system has been humming along pretty nicely for a few years, but lately I've been getting blue screens approximately every 32 minutes or so. But only when it's "idle"; never when I'm doing something like typing or browsing the net or running a local program.

Bluescreenview shows clfs.sys and ntoskrnl.exe, and it says it was caused by clfs.sys, mostly CLFS.SYS+a649 or occasionally CLFS.SYS+3e73e.

Things done so far:
inspected event logs; information level stuff, nothing funny before the reboot. There are 1001 Bugcheck reboot events over the last two days.
sfc /scannow (a few times, no integrity violations)
chkdsk /f /r /x
memtest on each 4 Gb module
uninstalled programs, including avast AV, disabled drivers and startup problems galore

I've attached the latest minidump if anyone can glean anything.

I really haven't done driver verifier much, one time it resulted in me having to restart in safe mode to disable it.

Suggestions as to what I should try next?

10Q!

I should add that I just got done letting the computer sit for a while in Safe Boot Minimal and it did NOT crash. So guess I'll start doing the selective driver boot thing.

Just wanted to update. I started removing drivers from boot. Removed all non-MS and Intel drivers. Still problems. But now my BSOD dump mentioned HECIx64.sys along with clfs & ntoskrnl. So after doing a bit of research to see if it was safe, I disabled that driver as well as the heciservice.

Left the machine on overnight and NO BSOD!

I then re-enabled all my startup programs and previous disabled drivers, keeping the heci stuff disabled.

NO BSOD!

I am going to let this run for a bit but it looks like my problem has been solved. Will mark solved later if all goes well.

Well it ran fine for about a day. Now I'm getting the CLFS / NTOSKRNL BSODs again.

Suggestions, anyone?

No one? This a pretty consistent problem that occurs approximately every 30 minutes. There HAS to be some way to figure out what is going on just before the crash.