2009 kernel hangs on amd mp when uni processor kernel chosen

[Gianluca Cecchi]

For error I started the uniprocessor kernel on a dual MP 2200+ system
and I noticed that
the uniprocessor 2.6.15-1.2009.4.2_FC5 kernel hangs up. The smp one is
ok instead.
Tried two times with same result.
The message is:
BUG: soft lockup detected on cpu#0!
PID:0, comm: swapper
EIP: 0060 [<c01394fe>] CPU: 0
EIP is at handle_irq_event+0x17/0x4c