Computer locks when certain USB devices plugged in.

I have a WD external Hard drive that now locks the computer when ever it is plugged in also a Multi Card reader. I have tried most of the recommended solutions but still when ever I link one of the above the computer locks and I have to hold in power button.

I have tried both devices in other USB ports but it does the same thing. I hope someone can help as I have an external hard drive I cannot use and card reader that cannot be used.

Please help.