Alt-SysRq-B doesn't work in recent 2.6 kernels

Now that my oops-on-boot has been fixed thanks to many on lkml
and a spot-on tip by Len Brown, I'll chase another one of the issues I still have :)

The problem in $subject happens reliably at least in 2 cases:

1. after the ACPI oops-on-boot (-mm tree and 2.6.2-rc2+)
2. in 2.6.2-rc1+ after the Cisco VPN client daemon (cvpnd, v.4.0.3.B) gets stuck in D state [__down] and I try to shutdown but obviously that gets stuck in turn

In both cases I can Alt-SysRq-{P,T,S,U,O} [though in case 1
Off only prints out "Power Off" but doesn't actually do it], and when I attempt a Alt-SysRq-B I only get

atkbd.c: Keyboard on isa0060/serio0 reports too many keys pressed.

and no effect at all.

Available for testing, as usual :) thanks in advance & ciao,

--alessandro

"Two rivers run too deep
The seasons change and so do I"
(U2, "Indian Summer Sky")