old MSA1000 disappers from Server

[Phil Scher]

I have a setup of:

an old MSA1000 with all 146GB disks. One single server (DL380G2) connected directly to MSA1000 via 2 FC card in each MSA controller

Server is running 2003. both OS and firmware are fully patched.

My problem is that once in a while (no pattern) the server looses connection to the MSA. First one controller then the second (could be several days after)
The only message in Servers eventlog is 3 of these messages in a row:

Event Type: Error
Event Source: PlugPlayManager
Event Category: None
Event ID: 12
Date: 25-03-2008
Time: 15:59:21
User: N/A
Computer: DBTEST
Description:
The device 'HP MSA1000' (SCSI\Array&Ven_COMPAQ&Prod_MSA1000&Rev_5.20\4&1f327568&0&000100) disappeared from the system without first being prepared for removal.

A reboot af MSA1000 takes care of the problem

I have changed FC cards, MSA controllers and cables....

Any idea whats happening?