Hyper-V backup - VM is Server 2003 - Froze VM

I was wondering if this has been seen before.  I have Netbackup Client on 2012r2 hyper-visor and I'm trying to backup a VM running Server 2003.  After 200GB of backup the VM server frooze and locked up(no rdp or from console just gray screen).  I canceled the backup and the VM server came back.  The VM is running a realtime application.  Would it be best to shutdown the 2003 vm and do backup while off?  I havent had a problem with 2012 or 2008 vms.

thanks,

M