Is it perhaps the case that your window manager is, now, as intended, compiz?
It's been a while since I introduced compiz/emerald to my LXDE box and I forget the details but I don't recall any specific problems. Can you explain in more detail what you mean by losing the WM (as in, are you booted out of X, do you lose lxpanel, do all the windows disappear) - further, is there any worrying output from terminal subsequent to the command being entered (presuming that you can see the terminal at this stage, of course

).
Thanks.