Yes, MS is constantly making small tweaks to Word, so that could be the problem. BUT, normally the tweaks should not have this sort of effect.
Actually, the best thing to do is ask this question at Perrla support. If it is a general problem, they will hear about it faster than we will here. Actually, this is the first time I've heard of Perrla.
It sounds like a problem with your normal.dotm, where the styles you use have been changed. Find your normal.dotm and see if there is a backup copy that you can restore/rename to use. IF there isn't, try closing all Word sessions and renaming normal.dotm
to see if the regenerated normal.dotm will fix the problem.
@Find Normal.DOT / Find Normal.DOTM / Locate Normal.dotmhttp://addbalance.com/word/normaltemplate.htm
http://wordribbon.tips.net/T006072_Finding_Where_Templates_Are_Stored.html - Ribbon****http://word.tips.net/T000862_Finding_Where_Templates_Are_Stored.html - Menu
http://word.tips.net/T001668_Opening_a_Template.html
How to Open the Normal Template ****The links above show a few different ways of finding normal.DOTM .
Off topic:
How long have you used Perrla?
How do you like it?
Have you ever had any bad marks from professor for formatting issues?