If the midi keyboard is a usb connection, make sure to try several ports and see if the problem persists.

Yes, make sure you using a USB 2 port and not a USB 3 port for that keyboard.  If you are using a different port than the one you originally installed on, you might want to uninstall your driver and reinstall.
 
I assume that the keyboard has an external power supply, but if it doesn't and you can get one for it you might try that, too.