Currently Being ModeratedNov 26, 2012 1:26 PM (in response to serhatkar)
A late 2011 MBP comes with Lion and should not be able to run with Snow Leopard. (I tried that using my Snow Leopard retail disk) Downloading a Snow Leopard OS from the Internet has been successfully installed in a late 2011 MBP by some, but aside from the legal aspects, these versions may have additions/deletions/modifications that may be the cause of your problems.
I suggest that you delete Snow Leopard and do a clean install using Lion or Mountain Lion.
Currently Being ModeratedNov 26, 2012 1:29 PM (in response to serhatkar)
Backup files off the machine and secure erase with with Zero (or middle option in 10.7/10.8) the ENTIRE drive and reinstall your flavor of OS X.
A Late 2011 came with 10.7, not 10.6, so you must have shoehorned it on somehow and I don't beleive there are hardware drivers for 10.6 on a Late 2011.
Are you sure it's not a Early 2011?
Get 10.6.8 on it then upgrade to 10.8 via the AppSore, option click on purchases and reinstall.
Currently Being ModeratedNov 26, 2012 1:58 PM (in response to serhatkar)
If you had 10.8 on the machine, then your Recovery HD partition should be that.
Hold command option r and boot, use Disk Utility to middle secure erase the entire drive, then reinstall 10.8 fresh from Apple' servers.
You will need your AppleID and password, as it was a paid upgrade.
No need to go the 10.6 to 10.8 route (you can bypass 10.7)
Restore your free iLife from the 10.6 disks
Currently Being ModeratedDec 13, 2012 11:58 AM (in response to serhatkar)