It sounds like there is something wrong with the program.
Kompozer is a spinoff of Nvu and development/support has been slow. You are by no means the first to have this problem.
Rather than beat yourself up over it, my suggestion is to dump it, as it is not lending itself to your new hobby of webdesign.
If you really want to understand coding and templates, then look at these editors, in this order;
Alleycode -
http://www.alleycode.com/index.htm
It's clean interface, easy to use, and has enough power to make you happy without the headaches.
Don't be fooled by it's simplistic look.
Better to be coding than fighting software.
The company that puts it out offers
SEO packages, but won't nag you. A nice touch to garnish business.
When you skills improve then look at
AcHTML the freeware version
http://software.visicommedia.com/en/productsfreeware/ it's a bit dated, I believe it's ver 3, but was originally bulit by globalscape. There is also a FTP program which again is an old version from globalscape. Both are for the advance programming.
If you are into design and do not want to worry about code, but still have the ability to view it then look at
WYSIWYG Web Builder 6.1 http://www.wysiwygwebbuilder.com/
Pablo Software was a young student who wrote some fantastic freeware which materialized into a great editor. You can try it for free for 30 days. The price of $39.95 is cheap for all that you get.
By the time you understand building webs you be ready to move on to paid programs just for the shear power and if you are like the rest of us will keep your favorite small starter editor for quick uses.
I hope this helps - because tring to reproduce a quirk in the software or your machine is not an easy fix. If a solution is found, you will always encounter anouther problem.
It's more fun to see your creation work, then to fight the software tring to make it.
Keep us informed and don't be a stranger to the forum as there are several members who contribute and share their knowledge.
Maybe you be one.