Class 'CI_Base' not found

[eluser]Unknown[/eluser]
How to fix this error?

Code:

Fatal error: Class 'CI_Base' not found in D:\myproject\system\libraries\Controller.php on line 30

// sry, i dont have a better description

Thanks

[eluser]xzela[/eluser]
it's possible you have a bad installation. Try downloading the CodeIgniter files again and extracting them to another directory.

That's the only thing I can think of at the moment.