"Protected Mode" has been causing countless problems since it was introduced in Reader X.
I recommend disabling Protected Mode several times every day in this forum to overcome crashes, printing problems, and whatnot.
Adobe recommends that Protected Mode should not be disabled, but so far has not come up with any solution for all these problems. So in my view, disabling Protected Mode is the only way to get Reader working as expected.
P.S. I am working with a number of computers running Windows 7 and XP, and none of them has Protected Mode disabled. Yet, Adobe Reader XI works without any problems on all of these systems. I do not know what causes these problems with Protected Mode on some systems.