Recently I realized that the ADMtek 8211 driver wasn't working correctly
(NIC would claim to establish a link with an ad-hoc net but it couldn't
send/receive packets). It turns out that every time the checkforhang
handler was called by ndis_ticktask(), the driver would generate a new
media connect event. The NDIS spec says the checkforhang handler is
called "approximately every 2 seconds" but using exactly 2 seconds seems
too fast. Using 3 seconds makes it happy again, so we'll go with that
for now.