Almost every time I turn off the computer and want to turn it on It won't start, then I unplug the power cable and wait for some time(about 2-5 minutes) and turn it on. Then when it turns on you can see an error message "There is no keyboard device found". Then I unplug the keyboard and plug it again, only after restarting computer It starts. I tried both updating BIOS to newer version and changing the keyboard, but didn't help. Can anybody help me with this problem?