i will trying to send the file soon.though i think its hardly a file issue.
as long we monitor them via remote desktop, the renders are fine.
when we see a error being rendered , we restrt the Backburner server ,then the same frame renders ok.
the forest scene file is xref-ed in the main file.
windows 6 64 bit.
max2009 64 bit
we guessed it could be an power saving issue where some service are turned off by window when console are empty.just an idea.