Mount Points on Windows 2008 cluster

Hi,

I need your help with a 2-node Cluster.
The cluster is build of 2 Windows 2008 nodes connecting to their shard Disks
via Fibre Channel to our Netapp Filer.
My instance consists of disk R:\ and a mount point R:\MOUNTPOINT
We installed a SQL2005 Server on this Disk R:\ and the Transaction Logs on
the mount point.

From now on, any file system operation (copy, change of user rights) results
in a failure of the mount point disk. The disk changes to failed, execute an
chkdsk and goes back online.
After a minute or two, it repeats this over and over again.
If I format this disk and bring it as S:\ into this Instance, I can do
whatever I want on the filesystem an nothing goes wrong.

I tried this on several instance with different disks and can reproduce this
behavior.

Installed software: SQL2005, Netapp MPIO, Fujitsu-Siemens Serverview


Any suggestions on this strange problem?

Cheers,

Uwe