server hangs

[Luca Ferrari]

Hi,
I've got a 6.1 server machine that is exhibiting a strange behaviour: I'm 
running a bacula director and storage daemon and sometimes the server dies. 
I'm not sure at all it's a problem running bacula, but it is since I'm 
performing these backups I've noticed that the server dies without showing 
anything on the screen.
I've found in the kern.log the following:

Apr 26 12:38:49 backup kernel: [42955544.250000] ReiserFS: warning: 
is_tree_node: node level 20042 does not match\
 to the expected one 1
Apr 26 12:38:49 backup kernel: [42955544.250000] ReiserFS: sda2: warning: 
vs-5150: search_by_key: invalid format \
found in block 27958929. Fsck?
Apr 26 12:38:49 backup kernel: [42955544.250000] ReiserFS: sda2: warning: 
vs-13070: reiserfs_read_locked_inode: i\
/o failure occurred trying to find stat data of [3071 3094 0x0 SD]

that are the last messages before the server dies. The same messages appear in 
the messages file.
Any idea about?

Thanks,
Luca