itunes will not launch windows 7 64 bit

When I try to launch iTunes, it does not launch. It shows up in the task manager (Stalling out at about 15000 k memory) it does nothing else. I have done a full reinstall, I have tried from a different user account on the machine. I have deleted the preference files. I have tried to launch it in "safe mode" (By holding ctrl+shift) but that does nothing. I have tried to create a new library (Holding down the shift key when I start it does nothing). I run Norton Anti Virus. I am fully updated on Windows. I cannot start iTunes. I worked Yesterday afternoon. The song I was playing ended, and then itunes locked up. Since then, it will not start. Please, any help would be appreciated, I would really like to update my ipod.