My friends computer has an issue where it would randomly lock up. The entire system just stops responding. Mouse freezes too. Seems it happens more often when playing civ 5. Need to track down why. Currently we think it's due to faulty RAM, so we've got memtest running. Any ideas? Additional info: Sometimes when it freezes, The mouse still works for a lil while then stops. Also it seems the USB devices lose power at this point. No crash dump is generated. CPU is core i3, 8GB corsair XMS3, H61 MSI MoBo, HD4870 graphics, Antec PSU. Only a few months old. Has a new WD HDD and an old SeaGate HDD as secondary.