Problem with Ubuntu Gnome 12.10

[Marc Stephan Nkouly]

Good Morning
am a complete beginner at  Ubuntu Gnome 12.10 and even Linux,
i recently installed the 12.10 version but since some moment's i can't
get back to the default gnome3 after login i have look for advices on
line but it seems as if none ever had this problem.
so am confuse i wanted to redo the installation but am afraid to loose my files.
Am currently  using a Think pad lenovo t400 with 4 G of rams.
Please if there's any advice u can give me i will greatly appreciate.
Gnome really missed me please i wanna come back to it, the errors
message i was getting was Gnome Failed to load.
i have installed Cinnamon and now i can get back to gnome classic or
gnome 2D but when i select system default it take me to Gnome classic
and not to the default Gnome3 that it came with.
hope u can help
-- 
Marc Stephan Nkouly
bp: 223 Mankon
 Bamenda
cameroon

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 mcsteann at hotmail.com                mcstean_cmr at yahoo.com