Start > Settings > Control Panel > Services
Then stop any services that are Backup Exec. This may take a little while. Once they have stopped then you can restart the services. This will keep you from rebooting the server
Or
PStools... be careful with this one, since you can corrupt a database, if it is stopped... I would try stopping the job, and give the server some time to think about it (at least 30 minutes) PSKILL will kill any service running on the server
http://technet.microsoft.com/en-us/sysinternals/bb896649.aspx
Lyon