itunes freezing my computer by using all my cpu and memory

Hi I have high spec pc. It's got 4gb ram and itunes uses all of it. I can't do anything. It's basically crashing my computer. I'm using another pc to even type onto this forum. I have to kill the process to get rid of it. so how can this be fixed - is there a fix to the software or something? i can't be the only one with this issue. It's pretty bad. I just rented a movie I can't watch. I also paid for and downloaded 2 episodes of tv shows I can't play. Not happy. where's the fix please?!