I will post my failover configuration tomorrow as soons as i'll be at work

but to tell you, it's a basic lan failover configuration the only parameter i changed is the failover poll interval i put it to the minimum (3 seconds).
but here is a little description of my architecture:
outside
Switch ------------------------Switch
| 2 Crossover cables LAN + Stateful FO
PIX ------------------------ PIX
| (
Switch------------------------Switch
Inside
Unplugging the inside or the outside cable on the primary/active causes failover. OK
Reloading the primary/active unit causes faiover to the standby: OK
Powering down the Primary/active unit make nothing!!!
When i type a show failover on the standby unit in this case, the result is that the status of all the interfaces is Normal!!! although i can't ping any of the interfaces!!
I'm wondering if i'm having this result because i'm not using a dedicated switch to connect the 2 units...
Thanks for your help..
HTY