Every helpful feature in Dreamweaver has a set of headaches. Templates are no exception. This page will be a list of the headaches I have and that my students tell me about.
Headache #1: Dreamweaver tell you you are outside the editable region, but you aren't.
You are working on a table inside an editable region, and you get this error message: "You have made changes to code that is not marked as editable. If you retain those changes, they will be lost the next time you apply a template update to this file. Do you want to retain the changes until then?"

I made this error show up in a templated page by inserting a table and then removing the line of code </tr> from the first row of that table. You can go to my code by clicking here and viewing the code. I put <!-- ******* --> where the </tr> should be. Dreamweaver is confused because it's looking for the other </tr>. It keeps looking until it gets outside of the editable region. Then it freaks out because it's broken the rule that you can't do anything outside the editable region.
If you look at the page in Internet Explorer, it will probably show the page just fine, except that the second cell in the first row is a bit different. Save the file to your web site and the template to your Templates folder and open the file in Dreamweaver. To find the template go to http://thecomputergal.com/Templates/GalInside.dwt. Your browser may monkey with the addresses a bit; so you may have to change them, but hopefully, you will see the error when you open the file in Dreamweaver. In fact, in Design View, the page content may disappear altogether. Remember the problem is that Dreamweaver is set to protect the template system, not that the browser can't deal with the code error. After giving you the error message, Dreamweaver's response will probably be to not show you the page content - or anything on the page - even though all the rest of the code is fine!