My computer is broken!!!

On my User account when i log in and try to open internet explorer, windows media player, my i-tunes or the control pannel, no window comes up. When i double click the timer come up but then it disappears and nothing happens. I am still able to open documents like Word. Also, when i log into my guest account i can acess the internet and the media player without any problems.

When i come to shut down the computer in my personal user account, a message appears that the internet explorer is still open and that i need to end the program before i can shut down the computer - even though no window ever appeared!

Has anyone got any idea why this is happening?