What cause dynamic highlight to turn off?

I was frustrated to no end with 2011 and the dynamic highlight.  My hopes were it would be fixed with 2013.  But now that we have upgraded (about 2 months ago) the problem still exisits.

I check dynamic highlight, it works great for an hour or so then decieds to turn itself off.  I click on Tools, Options, Display/Selection, Dynamic Highlight several dozen times a day.

Is there some magic feature SW built in for me or is this a software problem?