ToME: the Tales of Maj'Eyal

If I tab somewhere else, b43 just goes blank, dead, unrecoverably crashed, all I can do is shut it down.

I have that same issue on another computer (but not this one). After alt+tabbing the window won't come back up. What I found that worked (and this is a bit silly) is to change the taskbar setting 'keep taskbar on top of other windows'. For some reason that brings the window back up.