Hi Willem, during the installation process you select your language, keyboard, etc. Try testing with the live CD before installing and see if there's a difference in how you mouse works...or doesn't?
Thanks for your comment. The live CD works just fine and there is no problem at all with the mouse or the mouse clicks, only when I try to install the OS. I can, of course, get LXDE from the GNOME version by installing LXDE on the same partition from synaptic. That worked, but I am not sure if I then get the same version of LXDE.