If the external works then the laptop is at fault, you might get some mileage by reconnecting the keyboard ribbon cable but will probably be best to warranty the thing. More than likely the laptop keyboard is at fault, plug in an external and see if it works. What you are saying makes complete sense but, as far as I can tell, it is not an hardware problem. If not, keyboards are cheap and generally easy to replace.
If the unit is under warranty, contact Sony for a replacement. What is the relationship to AD? My vote would be a faulty keyboard. So whoever wrote your software has control of its behaviour. Block users in what application? The Cntl-B combo is controlled by the app. Sometimes it is just a matter of insisting. I was not able to figure out how I get it working again.
