Macbook Air Acting funny
First step would be to try a safe boot per Apple's support pages:


  If you're using Mac OS X 10.2 or later, you can start up your computer
  in Safe Mode, which includes an automatic disk check and repair. A
  Safe Boot, which starts up your computer into Safe Mode, may allow you
  to start up your computer successfully using a reduced version of the
  system software. To do this, follow these steps:
  
  
  Start up in Safe Mode. Instructions on how to do so are located here.
  After the system has fully started up, restart your computer normally.
  


Additionally, you may reference this page of Apple's support pages for other trouble shooting measures to resolve common startup and performance problems.