Looks like the update has elements which don’t get along with older parts of the Symantec program, and has been crashing home and business computers.
The reports started coming in on 7/11/12. After updating, a BSOD resulted.
So far, 300 corporate and 60 home system crashes have occurred.
Symantec has offered a solution: Rollback of definitions until a final fix has been made.
So, if you have the software and haven’t updated, DON’T!
If you do have it, and have crashed, contact Symantec for the fix.