ubuntu 12.04 freeze :(

[hani270]

previously, i was working on ubuntu 10.04 without this problem
NOW, i have installed ubuntu 12.04 and it's so beautiful,, it's completely with my hardware (touchpad, ati card ..... etc)
i have installed some applications i need, like netbeans, vlc, google chrome, gimp, pidgin.... and other apps.
but sometimes my laptop fully freezes ,, i cant move mouse and keyboard not responded.... i cant do anything except for press power button on my laptop for 7 seconds to shutdown
often, i get this problem after few seconds of the laptop return from suspend..
i have this laptop:

dell inspiron n4030
Intel® Core™ i3 CPU M 370 @ 2.40GHz × 4 ,,,
4 GB of ram
512 MB ATI Card -- Mobility Radeon HD 5430 Series
ubuntu 12.04 64-bit

[Manuj19]

Same problem here mate

[shirik]

Same problem here. I tried to reinstall gnome-shell instead of unity but issue is still here.

Edit : I have installed ssh server and no freeze during whole weekend. I connected only few times but no issues. After I got back to computer freezes return.
Edit2 : I am sure that everytime was started pidgin, thunderbird and chrome... I will try if any of these progs has issue

msi p55-gd65
i5-760K @ 3.8
16G ram
2x nvidia gtx 460
ubuntu 12.04 64bit