Have a recurring problem when an update for iTunes is available...Had my laptop serviced last December and they were able to update then, but before that, and presently I cannot. Same error window pops up, "invalid signature". I have no idea what that means, or how to fix it.
iPad, iOS 6
Same error window pops up, "invalid signature"
That suggests that the installer is getting damaged during the download.
I'd first try downloading an installer from the Apple website using a different web browser:
http://www.apple.com/itunes/download/
If you use Firefox instead of IE for the download (or vice versa), do you get a working installer?
Can't update iTunes
