Itunes error when trying to update! Says it might be a hazard to my computer and the win23 error.

Every time I try and update my itunes it says it will take an hour then after 4 or 5 minutes it says the program could be hazard to my computer. I click download anyway and after another minute it gives me the win23 error and shuts down. None of my devices will sync either. Apple refuses to help me. I am so frustrated!! Someone please help. I wanted to have some new songs on my Iphone for a day long trip leaving tomorrow.!!!

thanks