Download and apply the 10.6.8 Combo updater. Then download software updates to bring your machine to the latest level. Then restart your machine.
Mac OS X 10.6.8 Update Combo v1.1 Be aware, it does take time, sometimes around 40 minutes. It is a big update.
The download may have been tiresome but it will be beneficial in general. But it should have brought your iTunes right up to date. Below is a link to a similar question which you might explore
Have you tried to drag a copy of iTunes from your application file to see if that offers anything. Right click on the app first and get info. What version do you have and is it suited to your machine. It should be, following the update.