10.04 switch off trouble

[camuzat.sebastien at free.fr]

Hi all !
I hope I won't post a question that has already been answered...

On my Dell D600 laptop I installed Ubuntu 9.10 and it works very fine (except mouse freezes in some cases but that's not the topic of my post).

For a try, I also installed the 10.04 version.
It also works, except that I cannot switch the computer off, in that version. Mouse over 'switch off' does not do anything. Terminal command is the only way out.

Id like to upgrade another laptop (nx6110 under the brave old gutsy) but i do hesitate now.
Any advice ?
Sébastien.