VirusBarrier X5 provides the ability to run scans at specified times, and also to have scans run automatically when certain events occur. Schedules are useful if you want to make sure your Mac, a specific volume, on a specific folder, are free of viruses.
Events are either when volumes are mounted (such as an external disks that travel among different users) or when you download and install new virus definitions with NetUpdate. In the first case, you want to make sure that volumes that have been connected to other Macs can’t infect yours, and in the second case, you should run a full scan every time you update your virus definitions, in case a file you got recently is infected with a newly discovered virus.

Control either of these automated scans from the Schedule & Events tab of VirusBarrier X5’s preferences.