The recent update of iTunes to version 10 done via the Software Update is giving some users problems when they try to launch iTunes after the update. They get a message that iTunes is corrupt and needs to be reinstalled.

Don't panic. Nothing is wrong with your music library or your computer. Everything is still there.

As the notices instructs, you simply need to reinstall it. Do not bother try doing this by running Software Update again. You need to download the iTunes 10 installer directly from the Apple website by clicking here.

Your iTunes should be fine after the re-installation.