Symantec Scan Engine (SSE) 5.1.x/5.2.x occasionally hangs or crashes when updating its definitions via Intelligent Updater (IU).
This is a timing-dependent issue due to a race condition.
Delete "shadow.iu" after Intelligent Updater's download is done and re-create it after the definitions are updated with the IU as shown below:
This document assumes the environment in which IU is automated with some scripts and cron jobs on LInux and Solaris, with batch scripts and Windows tasks on Windows. Add the above two steps, disabling and enabling setup-iu.sh / setup-iu.bat, in your script.
Scan Engine 5.1.x or Scan Engine 5.2.x with Intelligent Updater enabled