Thanks, found the logs.
Sorry, Guillermo, I should have been clearer...I'm looking for the error logs because this same issue has reared it's head again. I don't know how to tackle it - but things are not consistently displaying with the theme. I am not having problems, but several of the teachers are and many of the students are finding (even having never logged in before) that the site is displaying without theme.
I've purged the site cache and helped users clear their own caches. I did things (as best I can) from the previous recommendations, and each time have had a period of stability (it would seem).
Do you have any other ideas what could cause this?
Thanks again for your time,