I have a Dell PowerEdge R515 server (with an AMD Opteron processor), running Windows Server 2008 R2, SP1. I have connected several different USB devices to this server and they all show the same error in the Device Manager: The digital signature for this device could not be verified... (Code 52). Is it the server or Windows? I have searched for drivers for my Toshiba and Western Digital external hard drives, but haven't found any as they are supposed to be plug-and-play.