FreeNAS crashing ... whats the Problem?

Hi guys,

i´ve configured the following system:

Board: Intel S5000VSA with 2xXeon 5120
RAM: 10GB FBDIMM ( 2x 4GB + 2x 1GB)
HDD: 10 x 2TB SATA
Software: FreeNAS-9.2.1.6-RELEASE-x64 (ddd1e39) on an 8GB USB-thumbdrive
Volume: ZFS on RAID-Z2 with all 10 HDDs each 2TB

On this Volume i shared 2 iSCSI-Volumes for Server 2008.
In the Beginnig everything works fine. I copied about 2 TB Data on the Volumes without problems.
After a few days i had to copy about only 80GB Data in 100K files an the...

FreeNAS crashing ... whats the Problem?