New build hangs after boot momentarily

New build, couple months old, see my sig below for specs.
After every boot, about 5 minutes into Windows, I always get a hang, always.
Can move mouse around, but showing system busy, system is unresponsive, keyboard no response, lasts about 1 to maybe 5 minutes then clears its self and all is fine.
Does not happen if I launch a game or program. If I launch a game as soon as I start Windows, I can play for hours, but when I close the game, bam. It happens within a few minutes. Its weird. Only seems to happen at the desktop, or when I have my browser open (Firefox) Once it happens 1 time, it will never happen again until I reboot, even if it is for several days.
Hard drive activity light will not be blinking, will be steady red during this.
I went through Toms guide on how to set everything up for an SSD?
I have installed all the latest motherboard drivers, did a repair install of Windows, everything is fast, smooth and fine expect for this annoying hiccup. Once the lockup has passed, I can leave the PC on for days with no issues at all. (which is what I have been doing)
What the heck? Anyone got a idea? Its' almost like some program is doing a background search for an update or something, or like the antivirus (avast) is updating and keeping the system busy, but not sure how to go about tracking down whats been happening or why.
Thanks for any suggestions in advance.