OK,
The OCZ's are not on ECS's compatibility list and are untested. This does not necessarily mean the the OCZ's won't work with this motherboard. After searching around the net I can see that others are using the same combination of motherboard and memory. No known issues as far as I can see, however it's still early days for such a newly released motherboard.
Everything else checks out.
Again... all inconclusive, and I would have expected memtest to complain if there was any real issues, however there is still the random element of your problem.
There's nothing more (at least that I can think of) that we can do at a software level to diagnose this problem. The next step is to take your PC apart, and remove any unecessary hardware, cd-roms, your second HDD and any expansion cards (if any). You should be left with your Power Supply Unit, motherboard,
CPU, fans, 1 stick of memory and your primary HDD to test with. Are you still left with the same problem?