Hi,
1. Which security software is installed in your computer?
2. What is the exact error message that you get with the error: 2324?
3. Were you able to install itunes updates successfully?
4. Have you tried uninstalling itunes apart from Bonjour?
I would suggest you to try the following methods and check if it helps.
Method 1:
Run the fixit from the following Microsoft Fixit article.
Diagnose and fix program installing and uninstalling problems automatically:
http://support.microsoft.com/mats/Program_Install_and_Uninstall/
Method 2:
Try removing and installing the latest version of itunes and check if it helps.
Uninstall a program: http://windows.microsoft.com/en-US/windows7/Uninstall-or-change-a-program
Download the latest version of itunes from the following link: http://www.apple.com/itunes/download/
Hope the information is helpful.