Is it the same days of the week every week? If so, are there any backup jobs that you run ONLY those days?
If yes...then yes it's probably Veritas.
If no...then it's something else. It could be something combined with Veritas, but it's not your job alone.
Here's a way to test....change the time of the job and see if the firewall still crashes.
If it still crashes a few minutes after 8, it's something else running at that time.
If it crashes a few minutes after your new time, yes it's your job.
If it doesn't crash, there's something running at the same time as your backup and the combination is causing the crash.
-SQLBill