This is an old and intermittent issue caused by real-time scanning deleting itunesprefs.xml which stores your preferences. A quick fix is to temporarily disable real-time scanning when closing iTunes.
There's a long thread about it here already: https://community.mcafee.com/thread/58410?start=0&tstart=0
I am stirring the pot to see what can be done, however it is really an Apple software coding problem, but it seems from an even longer thread at Apple Forums that they aren't acting on it so we shall have to wait and see if McAfee can.
I've been told that support are looking into this issue again.
Those of you with Anti-Virus build 1722 and higher should already have the fix, which was released on Wednesday with the regular update. Support did not make a huge fuss about it because they wanted to be sure it worked for everyone. You must appreciate that not everyone's setup is the same as that in the developer's lab so they are relying on responsible feedback.
We will relay it back to them.