There's going to be an action somewhere that is indicating that the backspace key be pressed.
What you'll want to first do is try restarting VA and then changing over to a different (non-HCS) profile. If that solves the problem, the issue is within that profile. If that does not solve the issue, you'll want to disable plugins temporarily to see if that changes anything. To disable plugins, go into Options > General tab, and uncheck the box labeled, 'Enable Plugin Support'. Restart VA and see if the problem persists.
Hope that helps!