Hi - I have a DH67CL motherboard with I3-2120 processor and 4 Gb RAM. Recently I've been having problems where unplugging a USB device from the back-panel ports causes the PC to reboot as though the reset button had been pressed. Sometimes the problem can be made to occur just by touching the cable without removing the device. Examples are VX-3000 webcam, keyboard and mouse. I've updated BIOS to latest level (160) and chipset driver is 18.104.22.1681.
I've installed a 4-port PCI USB 2.0 card where the devices work fine, but if I put the keyboard there it's not picked up a boot so I can't enter BIOS. Hence the keyboard must stay on the built-in ports.
OS is Windows 7 Home Premium, 64-bit and at current maintenance levels.
OK - think I've sorted it. Turned out to be a faulty power cord: the slightest movement appears to have resulted in a momentary loss of power. I don't understand why the PC always rebooted instantly and didn't stay powered off.
Anyway I've replaced the power cord and it's a much tighter fit in the power supply socket. I can't reproduce the problem anymore so I assume it's fixed. Of course when inserting or removing a USB device the cable is close to the power cord, so one slight nudge ......