Host IPMI System Event Log Status

I have an IBM BladeCenter S chassis with three HS22 blade servers, each with embedded hypervisors that have been upgraded to ESXi 4.1, 260247.

I'm running vCenter 4.1, 258902

When adding hosts to vCenter, each of them appears with a Red Alert, which seems to be related to these Events.

Alarm 'Host IPMI System Event Log Status' on server changed from Grey to Red

Alarm 'Host IPMI System Event Log Status' on server triggered an action

Alarm 'Host IPMI System Event Log Status': an SNMP trap for entity server was sent

How can I find out further information about what these messages mean?

Thanks,

k.