Please note, comments below has reference to the specific critical
error message listed in this document.
It could be that communication was lost or something changed on the
NFS server (maybe it crashed). The backup script starts by default
at 21:00 and this backup took 5 hours and 40 minutes. Basically, the
archive for that changelog (in this example 20060727-2.log) finished,
it tried to move the file to the NFS drive as a log of what was done,
and it failed.
The fact that both errors are the same indicate that something changed,
it wasn't just a once-off error.
I suggest checking the following:
1. the space,
2. check the Windows event log for NFS errors,
Only if all is okay, let it archive again and see if the problem still
exists. Alternatively you can also do a manual backup, but in this
case it's going to slow the machine down for 5+ hours, which is probably
not a good idea.