The log shows IO DBName is Frozen follow by thaw but yet my database schedule backup task which normally been running isn't since the network team are doing backs (not database backups, according to them) on the database server, using ArcServ 16.5. They run their backup utility around 11:00pm or later And my maintenance backup runs at 2:00am. This is in a 2000 SP4 environment. I would like to gather much evidence to show them that their utility is cause my schedule backs not to run.
You are getting this because something is having the storage array take SAN level backups. If you aren't on a SAN, then it could be something else on the server taking a snapshot of the disks for some backup purpose. If they are using ArcServ to take disk based backups (which I wouldn't consider an acceptable backup solution) that's probably what's causing the IO to be frozen.
Can you post more information about what is being backed up with ArcServ and via what process?
(Insert standard message about SQL 2000 falling out of support this month here.)