Well... that is what made me post this in the first place, it really didnt say much in the event log and nothing in the SQL Server errorlog...

but the miracle of a good nights sleep (and no kids in the bed to kick me in the groin every 15 mins) and i looked at the errormessage with fresh eyes this morning:

initerrlog: Could not open error log file 'E:\MSSQL10.BI\MSSQL\Log\ERRORLOG'. Operating system error = 5(failed to retrieve text for this error. Reason: 15105).

and i learned a new trick:

net helpmsg 5

returned :"Access is denied"

so i had a closer look at the permissions on the disks, and it appear that some permissions where missing!

probably a result of the disk change we made a few weeks back, so i set the permissions for the SQLserver and Agent on the proper folders, looking at another instance as a souce and now the failover to another node works great!

but why did it work in the previous node then?

it looks like someone has but this perticular SQL server service account in the local administrators group...

Thanks for the help, it got me thinking in the right direction!