Gnome 3 problem: all extensions turned off, all preferences lost

[custore]

Hi you all. I have a huge problem. I have ubuntu 12.04, gnome 3.2.1 (with win 7). I turned on my laptop and enter to my ubuntu session and it seems, that nothing was working: not the shell, not some links i had on the desktop, not shortcuts. Then I decided to turned off in the hard way. When start again, everything was working but all seems brand new: All the extensions i had were disabled, all my session preferences disappear (desktop image, font type and size, shortcuts, etc). So i decided to restart (because i had no idea of what else to do) and this third time my session preferences came back; the only thing i had to do was turned on all my extensions, that were installed but turned off. Ok, i said, everything nice, i can com back working, and forget it. However the problem came back the next time i turned off/on the computer (everything horribly like new :confused:). And this time, no matter how many times I restart it, there seems a no coming back. I really don't know if this is a gnome (3) problem but i suspect it because when i try to turn on the extensions (at https://extensions.gnome.org/local/), they do something really strange: I turned on the first extension, and when i turn on the second (any) the first that was activated, turned off automatically, right in front of my eyes.

I tried to google the problem but got no luck; i'm not even sure of how to search for it. If need any information of my system just ask for it (please tell how to get it, i'm half-noob)

Thanks in advance