iTunes App Update Crash

Hi. Ever since iTunes 11 came out, I've been experiencing problems updating apps on my computer. When I update any app, my iTunes downloads the app, but when it says processing file my iTunes freezes. Sometimes it is not just my iTunes, my whole computer freezes. I have a fairly good computer with 4 GB Ram and can run everything else without a problem. Please help me with this problem. Not having them up to date on my computer wouldn't be a problem if it weren't for these two reasons. Firstly (less importantly), the number beside apps showing me I have updates bothers me. Secondly, I want to be able to sync my iPhone and iPad to my iTunes Library. I can't do this because when I do it transfers my purchases to my iTunes Library. This is a problem because it the tries to install the app updates from my iPhone/iPad, thus freezing my computer. I hope this wasn't too long or wordy. I'd really appreciate any help I can get. What should I do about this problem.