iTunes and Safari FREEZING and won't letting me Force Quit! pweez help meeeee

Sometimes when I'm working on my computer, iTunes will sport the wonderful beach ball and upon right clicking the icon in the dock, the Force Quit option is displayed. If I Force Quit, iTunes will not go away until I restart the computer. However, if I kill it in the terminal [top, find number of running application, q, kill (# of app)] it will go away. The same thing happens sometimes with Safari. Totally random. It's happened quite a lot recently though.

Anyone have any advice?

Oh to clarify: If I Force Quit iTunes or Safari when it freezes and THEN try to quit it in the terminal, the terminal does not display it as a running app. Therefore if I Force Quit, I'm screwed until reboot.

Thanks!