Likewise, my install of 10.4 via SWU was giving the same error. I also noted that Get Info was giving a last modified date that was two days prior to the creation date.
Anyway, as suggested, I re-downloaded the standalone installer and ran it and this fixed the problem, not by now providing the 32-bit mode checkbox though! Instead, it just ran in 32-bit mode automatically. Of course, the other question that this begs is, given that Snow Leopard (which I'm still running) is a 64-bit capable OS, why won't this v10.4 of iTunes run in 64-bit mode?
Also of interest are that:
- the re-installed iTunes STILL says the app is version 10.4 (not 10.4.1 or anything else different to indicate that it's bug-fixed), and
- the creation date is now "Monday, 13 July 2009 22:46" !!!!!!!
Begs the question, methinks, of what on earth Apple's developers are doing lately with their software configuration management. (And, while I'm at it, I will also mention that Disk Utility's "Repair Permissions" function has been producing some VERY strange errors for quite some time too. After these latest updates, I ran it again and it's now even reporting that some files should actually be directories - AND saying that it's "fixed' them successfully! It doesn't, of course...... :-P )
Sorry, Apple, to be somewhat critical here, but as one who's worked in IT and been responsible for configuration management on various projects, I know I'd have had my A*S kicked severely if I had let software out of the door with these sorts of errors, so I don't think I'm being unreasonable when I expect a company like Apple to do at least as good a job as I can!