Comment 38 for bug 1308674

When working with external displays, it seems that:
a) every odd display disconnect leaves you with broken (minimal, nonadjustable) brightness
b) every even display disconnect seems to work properly (brightness can be adjusted)

I haven't tested this with docking station, but it's likely that it could work the same way. This might be at least some workaround, until this is fixed. Simply disconnect the display twice.