You'll need to completely uninstall iTunes from your computer. On a Window's computer with the iTunes download there's a few other components that help iTunes function. Sometimes it's one of these are corrupted causing an issue.
Steps on uninstalling iTunes for Windows XP:
http://support.apple.com/kb/ht1925
(keep in mind, if you have Windows XP Service Pack 2, the latest version of iTunes 10 will not download onto the computer as it is not compatible.)
Steps on uninstalling iTunes for WIndows Vista and Windows 7:
http://support.apple.com/kb/ht1923
One the uninstall is complete restart your computer and download the latest version of iTunes at www.apple.com/support
If the issue is happening on a mac, drag iTunes to the Trash and re-download.
NOW, if you're getting an error about the iTunes store not being able to connect, what you may want to try is creating a new user account on your computer and accessing the iTunes Store from that other user. Or, a lot of the time it's third party programs interfering with iTunes and not allowing iTunes to access the internet. Doing
http://support.apple.com/kb/ht2292 MSCONFIG will determine that since it will temporarily turn off all third party programs. If the MSConfig fixes the issue that means it's one of your programs causing the problem. One or the other should fix the 3212 error.