keyboard layout (USA) cannot be removed

[Thomas Blasejewicz]

Good evening from Japan
I installed TuxTrans - basically Ubuntu 10.04 but packed with lots of
stuff for translators - on a dedicated machine to experiment with it.

Question:
I am in Japan and use a Japanese computer (Hitachi Flora)/keyboard/language.
Although I specified during the installation to use a "Japanese"
keyboard, the default seems to be "USA".
Right clicking on the little icon at the top margin of screen after
adding German and Japanese keyboards:
Right click -> Groups: shows "Germany, Japan, USA".

I REMOVED the keyboard layout "USA" (don't need it) SEVERAL TIMES
already, but each time I restart the computer its layout is back.
Immediately after I removed "USA" there are only two KBs and I can
switch between them, but they tend to switch on their own while I am
using the keyboard for some other operations.
I noticed, that although I deliberately switched the KB to "Japan", it
switches back to "German", in particular, when I use the key combination
"Ctrl + Q".

Now, what is this all about. I have never seen any such behavior before
and I definitely do not want it. This is very annoying.

Is there a way to fix this?

Thank you in advance.