Asus P6T Deluxe V2
Intel i7 975
Antec 1200 case
PNY Nvidia GTX 295
OCZ 60 GB SSD
4X Seagate Barracuda 7200.12 in RAID 5
Windows 7 64Bit
You will notice RAM is not listed.....
I would leave the system come back and the the USB would be dead until I powered down and back up, sometimes overnight sometimes it would take two nights. I had it happen once while I was at the keyboard. All I was doing was running 7Zip. Other times, I ripped full DVD moves to HD with no problems. Hitting the reset button did not restore the USB power I had to power completely off and back on. I was seeing DVD-ROM mount errors in the system logs so I upgraded all firmware and still had the same issue.
On one reboot, I notice that my RAM had dropped form 6GB to 4GB which is the point I realized that my memory was junk and had to go. I'll updated tonight after I install the new memory. I feel like such an ass because I had the same problem the last time I built a system.