freebsd stable - Mar 2006 - Strange problem with STATUS of Intel MatrixRAID

Hello I have this problem:

Yesterday server with FreeBSD 6.0 was self restarted . In messages was this:

Mar  8 20:03:11 mail kernel: ar1: WARNING - mirror protection lost. RAID1
array in DEGRADED mode
 Mar  8 20:03:11 mail kernel: ar1: writing of Intel MatrixRAID metadata is
NOT supported yet
 Mar  8 20:03:11 mail kernel: subdisk8: detached
 Mar  8 20:03:11 mail kernel: ar1: writing of Intel MatrixRAID metadata is
NOT supported yet
 Mar  8 20:03:11 mail last message repeated 78 times
 Mar  8 20:03:11 mail kernel: ad8: detached
 Mar  8 20:03:11 mail kernel: unknown: TIMEOUT - WRITE_DMA48 retrying (1
retry left) LBA=326028767


 Mar  8 20:04:39 mail syslogd: kernel boot file is /boot/kernel/kernel Mar
8 20:04:39 mail kernel: Copyright (c) 1992-2005 The FreeBSD Project.
Mar  8 20:04:39 mail kernel: ad4: 238475MB <WDC WD2500SD-01KCC0 08.02D08>
at
ata2-master SATA150
 Mar  8 20:04:39 mail kernel: ad4: Intel calc=f72ede8c meta=7b976f46
 Mar  8 20:04:39 mail kernel: ad6: 238475MB <WDC WD2500SD-01KCC0 08.02D08>
at ata3-master SATA150
 Mar  8 20:04:39 mail kernel: ad6: Intel calc=f72ede8c meta=7b976f46
 Mar  8 20:04:39 mail kernel: ad8: 305245MB <WDC WD3200SD-01KNB0 08.05J08>
at ata4-master SATA150
 Mar  8 20:04:39 mail kernel: ad8: Intel calc=e722a4c0 meta=f3915260
 Mar  8 20:04:39 mail kernel: ad10: 305245MB <WDC WD3200SD-01KNB0
08.05J08>
at ata5-master SATA150 Mar  8 20:04:39 mail kernel: ad10: Intel
calc=e722a4c0 meta=f3915260
 Mar  8 20:04:39 mail kernel: ar0: 238474MB <Intel MatrixRAID RAID1>
status:READY
Mar  8 20:04:39 mail kernel: ar0: disk0 READY (master) using ad4 at
ata2-master
 Mar  8 20:04:39 mail kernel: ar0: disk1 READY (mirror) using ad6 at
ata3-master
 Mar  8 20:04:39 mail kernel: ar1: 305245MB <Intel MatrixRAID RAID1>
status:READY
Mar  8 20:04:39 mail kernel: ar1: disk0 READY (master) using ad8 at
ata4-master 
Mar  8 20:04:39 mail kernel: ar1: disk1 READY (mirror) using ad10 at
ata5-master

This is strange that raid tell me ad8 detached and raid is DEGRADED and
after reboot is quickly READY.

What does it mean? Bad disk,board, FreeBSD : () ?

In this moment on ar1 was written some big backup.


Thanks

	John