With backup compression enabled, Seagate BlackArmor Backup sometimes freezes when trying to back up several thousand files and/or folders, or when trying to back up System State in Windows Vista.
In both cases, invoking Windows Task Manager (CTRL-ALT-DEL -> Applications) shows BlackArmor Backup as Running.
This is an issue in the compression algorithm of Seagate BlackArmor Backup. As a workaround, set compression level for the backup process to None.