i'm wondering if the Novation Impulse 49 keyboard works in realband?
installing BiAB and realband only, no real tracks or other options in a different directory for test purposes may be an option
in the past when i've had issues like this i've used Autoruns for Windows v11.34
http://technet.microsoft.com/en-gb/sysinternals/bb963902.aspxto temporarily disable all but essential divers to try and determine which was Causing the problem