we are using BackupExec 2010 R2 (Rev 4164).
On a remote server (Server 2003) we've got the problem, that almost every time (in about 80%) we are running the backup job on this server, the windows firewall service stopps working.
The eventlog just says, that the service was stopped by "system".
...I'd go with updating Windows to be honest. Run Windows Update and patch Windows, and then run a backup again.
If it happens again, uninstall the agent, and reinstall it, and make sure that the required ports are opened for the RAWS agent to run correctly.