BSOD- HIDCLASS.SYS (ntkrnlpa.exe)

Ok so tearing my hair out: 5-6 BSOD's per day. I should admit I'm no expert & I'm flying by the seat of my pants really . Anyhow, dump report is attached & below is what I have attempted:

1. Admittedly old, but cherished, working PC- did clean install of W7 on new SSD (Samsung 850 Evo). Also upgraded CPU to "Intel Core 2 Quad Q6700"- tested ok on install. All good for c. 3 months
2. Regular BSOD's after 3 months
3. Clean re-install of W7
4. BIOS reinstalled
5. Bluescreenview reports- common denominator is "ntkrnlpa.exe"
6. Ran memtest86 overnight- No errors
7. Realised I hadn't installed W7 SP1 since W7 reinstall- eventually managed to install in Clean Boot. Still BSOD's with SP1 installed anyhow. N.B. attached report may or may not show SP1 installed due to Start-up System repairs/System Restore.
8. Driver Verifier gives immediate BSOD- "HIDCLASS.SYS". So a USB driver issue?
9. In Device Manager I have loads of HID-compliant consumer control devices/HID- compliant devices/USB Input Devices listed. The only USB device I actually have connected is a Logitech Wireless Keyboard Receiver. However also realised my "Hauppauge WinTV T-500" DVB-T PCI tuner card strangely shows-up as a USB Device. Tried uninstalling this but still getting BSOD's.

So where next? Can anyone help me given the attached dump reports? Is it a specific USB driver? Perhaps the CPU has failed, should I test this with Intel Processor Diagnostic Tool or similar? Could the Motherboard have failed? Many thanks, any help gratefully received.

Thanks for the reply axe0.

Yes I think you're on to something there, I have belatedly realised that Windows Update was not functioning correctly & that all updates had not been installed. Unfortunately the system is so unstable now that it just crashes if I try to run Windows Update (tried Windows Update Troubleshooter & the Windows Update updater etc). I am now reinstalling W7 again with the hope of getting stability & then all Updates installed.

BTW- Intel Processor Diagnostic Tool passed the CPU (with exception of SPBC & Brand String, which AFAIK don't really matter). Visually checked the motherboard capacitors & all seemed fine.