PC in sleep mode, locked by Norton Security?

Since installing Norton Security on 2014.11.26, twice I have found my Win 7/64 PC locked in sleep mode, not responding in 10 or 20 minutes after repeated mouse and keyboard prompts.  My only option was to force a hardware shutdown, boot to run CheckDisk, and do another reboot.  What a waste of time!  And the PC was switched off on nine of those 12 days.

Perhaps my troubles relate to comments in the December-2009 thread “Norton 2010 locking up computer during Idle Background Scans.”  The thread focused on disabling a process in Norton 2010:  Settings > Miscellaneous Settings > Idle Time Optimizer

Might the issue be affected by having two user accounts open simultaneously?  Any solutions?  I would prefer to use the automatic Disk Optimizer, but not at the cost of repeated locked-sleep recoveries.