Hello,
Please start your PC and after bootup, disconnect your Keyboard physically..
There is a feature called On Screen Keyboard.. Just type keyboard under search box of Win7 start menu to launch it..
*img695.imageshack.us/img695/1135/31549438.jpg
*askabouttech.com/wp-content/uploads/on_screen_keyboard.JPG
Use it (via mouse click) to see if the key functions are working properly or not.. If they do, then there should not be any issue with your OS and you can be sure that its a hardware fault with your keyboard.. Where as if still you face any issue, then yeah, keyboard is alright and there is an issue with your OS..
Thanks..