I have installed a Ubuntu command line system and then installed kde-baseapps metapackage 4.7. Also I have installed some applications and nvidia drivers.
Problem is that I can't disable desktop effects.
If I go to system-settings -> desktop effect and de-select all the effects they seems to de-select ,but when I reopen that panel I find again the default settings applied.
Is that a bug, or am I missing something?
If it's a bug is there any way to circumvent that?

If you want to disable desktop effects completely, just uncheck the first checkbox in the Desktop Effects control module. You don't have to go uncheck every single effect.

You can try moving the kwinrc file in your ~/.kde/share/config directory to some other location and starting fresh. This is the file that's actually being written to by the Desktop Effects control module.