MSA1000 bizarre errors

[CA1302229]

Hi All,
I have an MSA1000 with two controllers, two 2/8 switches and two MSA30s hangin off the back. 7 servers are plugged, two are clustered, the others are all single. 1 runs Win2003, all other run Win2K.
All has been OK, until I received notification of a disk failure. No problem I thought, one of teh spares will kick in and I can then replace the damaged disk. Problem is though that the ACU is showing that there is a "bad or missing physical disk in Box 0 Bay 0)" and this makes no sense to me. All the disk lights are on and green, so there is nothing visual to suggest a failure.
Now things get more strange. The array that is affected is ArrayB, with logical drives, 5,6,7 and 13. It is in a RAID 1+0 and I built that from disk 2,3 on channel1; 9,10 on channel2, 2,3 on channel3 and 2,3 on channel4. The ACU is now showing that disk10 is unconfigured.
Now things get even more strange. I ran the Array Diagnostic Utility and from what I can decipher, it is showing that for logical drives 5,6,7 and 13 the disk at port2 drive 8 has replaced the disk at port2 drive 7. Looking again at the ACU drive 8 is indeed my spare, but drive 7 is not part of the array that has the error!
I tried to have a look to see if I could expand the array and reintroduce disk 10 on channel1 back in, but I cannot.
I have attached as much information as I can and would welcome any thoughts on how I can resolve this. Thank you