Windows 7 Freezes When Idle?

hen the system is not heavily loaded it seems to freeze after 10 minutes to an hour, primarily observed with the Up Time clock in Task Manager stopping. Other symptoms include no response to keyboard or mouse clicks and having the cursor lock to a particular shape such as the window size adjustment shape. The only way I have found to get the system going again is to shutdown and reboot. Usually a hardware reset or forcing shutdown is required to get applications such as Task Manager to stop. When the system is heavily loaded i.e. running Prime95, these symptoms do not seem to occur.I have been unable to determine conclusively whether the problem is hardware or software. The system(s) are new with the following configuration[CODE]I have performed multiple clean installations of Windows 7 Pro from two different Microsoft DVDs (purchased from Newegg), used two different sets of hardware (including CPUs, memory, video cards, Power supplies, disks, etc.) changed from Gigabyte GA-X58-USB3 motherboards to GA-X58A-UD5 motherboards, run memory tests for ten hours or more, run in Safe mode, run with absolutely no additional software other that the virgin operating system. Tested multiple BIOS settings, including optimized defaults, with changes only to allow RAID disks.