Hello. Unplug all devices attached to USB and PS/2 ports. Disconnect the AC power cables, wait about 1 minute and then press and hold the power button for about 15 seconds. Reconnect the power and power on the server. Connect the keyboard and mouse to the USB ports and try again.
Good afternoon everybody.  Yesterday I pursached a second-hand Dell Poweredge 840 to run as a backup server, I am having some problems with it however that I cannot figure out.  I installed the server with Windows Server Edition 2003 x86 and downloaded the drivers from the Dell website. It works flawlessly, except for one problem:USB keyboards and mice refuse to work. PS/2 works fine however, but any USB keyboard or mouse refuses to work.  USB Flash drives do read fine, that's the way I used to get some files on the machine before it was connected to the network, but USB keyboard and mice won't work.  They are not recognized upon boot and do not allow entering the BIOS setup, after Windows startup they are still not recognized. Windows shows the device as an unknown device.  I tried booting off a Lubuntu 14.04 live CD, in which the USB keyboard and mouse wouldn't work either. Only PS/2 wants to work.  I tried some different types of USB mice:  None of these would work, although they work fine on my personal laptop, the main fileserver which is a HP model and a Dell Optiplex desktop computer.  I tried a couple different USB keyboards as well, but they refuse to work.  I ended up borrowing a pair of PS/2 keyboard and mouse to setup the server, but I would like it to work with my USB keyboard and mouse. Just for the record: USB flash drives do work fine, it's just keyboard and mouse that won't work.  Does anybody know how I can make this happen?  Thanks in advance, Dominique
Poweredge 840: USB Keyboard and mouse not functioning.