The remastered version of the Ubuntu linux with Compiz preinstalled on it might have some working problems on some machines... I have to face the same situation in some of my friends machines with AMD motherboard, when I tried to install a version of the Ubuntu which is remastered using an Intel PC. Here is a simple solution through which i have solved this problem to an extend.
1. Click on the Compiz Fusion Icon from Applications >
System Tools
2. Right click on the Compiz Fusion Icon on the panel
to open up the menu. Select Compiz from Select
Window Manager
2. Click on the Reload Window Manager to reload
the compiz window manager.
3. Change the Visual Effects to Normal or Extra. Right
click on the desktop and select the Change
Desktop Background and then Visual Effects.
4. This might be enough for loading compiz. You can
add the command 'compiz-decorator' to the
startup applications to automatically launch
compiz on logon.