I have the same problem when using the r52 with the same adapter, when I enable the card mikrotik fell, I've more mini-PCI, and all normal work. Do mikrotik rb11 adapter can do the work
On this AP is 10 users conect. Minipci R52H ,Polarisation Vertical, B standard ,antena is Sector 14db 120H/30V, This problem hapend couple of day. Users use Yagi and grid antenas.