After I've reinstalled Mac OS X 10.8 and transfered my back-up folders to my MacBook Pro (late 2011), all Mac OS apps started to crash as I open them. I'm talking about apps like Mail, Safari, Keychain Access, System Preferences, but also some other apps like Xcode or Skype. I've tried to format the whole HDD and re-intall the OS and retransfer my back-up files, nothing changed. I also can't access some sites like gmail.com or do some googling directly from the navigation bar of Google Chrome - it says that the webpage is not available (not sure if the issues are related but started at the same time).
What should I do to use the computer correctly?