Yes, what have I done? I don't want to discourage anyone from helping by just dumping a bunch of data. So I am trying to provide a more spare description hoping that more experienced users will be able to offer an insight. That said, here is a brief rundown of possible events over the past couple of weeks leading up to this problem.
One, I do a daily backup but only keep two back up days before replacing the oldest with the newest. It seems that whatever I did it was done more than two days ago, because reinstalling site with .tar didn't fix the problem.
Two, in my theme/styles folder, I created a new .css style sheet to enable the creation of several rollover items in some pages in a Topic. These were basically built on an imagemap as a container using <UL> and <LI> options which were then implemented in the TinyMC editor HTML. I developed these .css classes and ids over about a two week period. I would build a class or id in the style sheet then purge my cache and test it (I did not turn off caching, just cleared them after a .css revision) They all seemed to be working fine until when I first noticed the problem with Topic Headers a couple of days ago. First thing I did was to remove this .css style sheet and mark it out of the themes.php list. I then tried creating new courses with new topics. But the problem persisted.
Three, in working on the Course and its Topics, I have installed a couple of new plugins.
a) To add drag and drop markers on image question types I installed DDimageortext, DDmarker, and Gapselect. While in student mode reviewing a quiz based on DDmarker questions I first noticed a display problem with a question header. It worked fine in Admin mode, but not in Student. Working on these quizzes was the last thing I was doing before seeing the problems. I had been working on them about 3 or 4 days.
b) I installed, but have not used, the sharing cart plugin. My intention for it is to move some of the topics and quizzes created in this current course into a new course.
c) I installed the navbutton plugin which required a modification to the outputrenders.php, but I could never get it to work, so I uninstalled it and removed the modification code.
d) Also thought that I might have messed up the Rocket theme while reviewing some of the .css file structure, so I reinstalled the theme. I also switched to the basic theme to see if the issue would go away. It didn't.
This seems to about sum up the activities in which I have been engaged over the past two or three weeks that I can recall. Generally, I try to be very careful about moving around or changing items and I try to evaluate everyday so that if I have a bad problem I can reinstall. Obviously, it got away from me this time.
Any suggestions or comments, please.