First, please try the latest development build from the forum here:
http://www.aqua-mail.com/forum/index.php?board=9.01.5.1.16.17 or later (1.5.1.16.15 had a change in how HTML content is prepared for displaying).
Other than that, sorry, I don't have any ideas.
From my point of view, the presence of those apps (LastPass, 1Password, Norton) that "get into" other apps using Android's accessibility functions -- breaks something inside Android WebView, which is a system level component for displaying HTML (you can think of it as Chrome browser, or more exactly, Chromium, inside an application).
It's also difficult to reproduce -- for some users it seems to happen pretty consistently (quite few users, it seems) -- but I wasn't able to make it happen.
Why it breaks and what to do to prevent it -- no idea, really. I already had a discussion with the lead developer of LastPass, which ended up nowhere, he seems to think it's a bug in Android / WebView itself, and that's where it ended.