I hope these steps help.
1) Make a new user - the steps are in http://support.apple.com/kb/HT1199
2) Log into that user, open iTunes, agree, etc. - it will probably work
3) If it does, it tells us that iTunes (the program) is fine but it's encountering something unexpected
4) Go back to your user, and try to open iTunes while holding option and making a new library - like suggested in http://support.apple.com/kb/HT1589
5) Your iTunes will be empty. This is ok. Your files are not touched by this process.
6) If iTunes doesn't quit when loading an empty library, you could try rebuilding the iTunes Library as Apple documents in http://support.apple.com/kb/HT1451
7) If iTunes does quit, it could be trying to grab something - like photo information to sync to your iPad - and that's where it finds the unexpected data. Maybe try moving the iPod Photo Cache? http://support.apple.com/kb/TS1324 should guide you for how to do that.
If you tell us whether it is library-specific, user-specific, or system-wide (happens in both users), we could maybe give you better advice on what's going on.'
If the new user has the same behavior, maybe remove the SC Info folder - there are not many system-wide files iTunes touches. http://support.apple.com/kb/TS1389 covers how to remove that invisible folder.
iTunes uses /Applications/iTunes.app, /Users/Shared/SC Info, ~/Music/iTunes/ and ~/Library/Preferences/ and a bunch of other files. I think the most effective way to help you is knowing whether the issue is system-wide or user-specific.
I hope this helps and feel free to reply if this is all confusing.
I made a new user profile and tried to load iTunes on that account. Just like on my account, it wouldn't open. Although this time, instead of crashing, the icon would just bounce up and down endlessly until I force quit the application.
I also tried deleting the SC folder. After I had reset my computer, I tried to open iTunes again but it didn't help at all. iTunes is still crashing on startup.
I guess this means that because iTunes wasn't working on the new user; the problem is probably system-wide. Is there anything else that you can suggest?
Maybe 32-bit mode will work, maybe Safe Mode will work, maybe removing QuickTime components will work... otherwise, I'd check with AppleCare to see if you're eligible for support because of Mountain Lion.