Twitter.com disabled Basic Authentication on Aug 31, 2010. This means that sites which integrate with Twitter may no longer do so using your Twitter username and password. As a result of this, I've updated the WunderCounter's Twitter integration to use OAuth, which Twitter has switched to fully now.
This means that when you enable the WunderCounter's Twitter features, like getting a daily summary of your stats via a Twitter DM (Direct Message) or getting a DM when certain IPs visit your site are still available to you, you do so without providing your Twitter password. Instead, you'll be forwarded to Twitter where you may give permission to the WunderCounter to access your account. This permission may be revoked by you at any point and, since you don't have to reveal your password, it's more of a "feel good" experience. :)
WunderCounter's Twitter OAuth is now live. You can get to it by selecting "Twitter" from the "Options" menu after logging in to your account.