Z, the only thing that seems to have a statistical scatter over the last six months is Windows Update malfunctioning. It can be fixed.
Have you checked your Windows Update history recently? If it shows a date much earlier than mid-April or in some bygone month, it's a problem but it can be fixed.
Do you watch your CPU clockcycles? (I assume you still have the SB and Z68 or IB and Z68-Pro-Gen3.)
I only noticed my problem because I could barely hear the fans kick up, so you could easily miss it. If thermal monitoring shows one core reaching close to 50C for periods of time and about 14% CPU usage, take a look at your SVCHOST processes in Task Manager's Process-Tab.
Then run Windows update and see if it gets lost in a perpetual cycle of checking for updates.
Those are some of the symptoms many -- not all -- have faced in recent months.
This would all be different for either an older, C2D, or newer processor. The problem with my mobile C2D showed 50% usage by one single SVCHOST running on one core, even if two threads.