The Server Schedule in Network Assistant 4.0.1 is configured to open Disk First Aid and rebuild the Desktop file of network clients at a scheduled time. If the clients are turned off and miss the scheduled time, a bus error occurs when the computers are restarted and the Network Assistant system extension loads.
Solution
Download and install the Apple Network Assistant Updater 4.0.2. The North American English version of this update is available from the Apple Software Updates Web site at http://www.apple.com/swupdates.