Sorry Italo – the list in the manual covers cards which are NOT compatible.
This sounds like the sort of problem that cannot easily be resolved remotely. It may be one or more of the following:
1) The computer and whatever else it is doing
2) The firewire board (less likely if you've tried different ones, but still possible)
3) The firewire cable and connections
4) The H8000.
Easiest thing is to disconnect all other firewire devices and applications, and try a new firewire cable. If this fails, try a different computer. If this fails, the H8000 should come back.
My guess is that it is a computer issue at your end – typically the firewire hardware in the H8000 either works or it doesn't.
