Ubutu 12.10 login loop

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http://askubuntu.com – I just installed Ubuntu in dual boot with windows 7.. I'm new to ubuntu so i found it very hard to install nvdia drivers for my nvdia graphic card.. I tried following some guides, with no luck and now my ubuntu login screen is stuck in a bootloop. It asks for my username password, i enter it correctly, then a black screen appers and quickly returns me back to the login windows asking me for my password again and again. How to resolve this issue? (HowTos)