Another variation on the Twitter account authorization issue.
In addition to my live website, I have a version I run on a local server to allow me to try things out, tweak CSS etc. before I make changes to my live site. I successfully installed Twitter Widget Pro on my local server, authorized my Twitter account, and it all worked beautifully!
So I then decided to add it to my live site. Unfortunately I (foolishly, it seems) tried to use the same Application with the same Consumer Key and Secret as for my local site. That didn't work, so I tried making a new Application on the Twitter Dev site. Even using the new details it still didn't let me authorize my Twitter account.
Interestingly, after I click the Authorize New Account button, I'm taken to the annoying page that says "Whoa there! The request token for this page is invalid." However, when I go to the "Apps" tab of my Twitter account's settings, it lists the App there (and it is the new one I created for my live site, as I gave it a different name). So it seems Twitter considers the App to be authorized for my account but the plugin doesn't.
One thing I'd like to try is to completely uninstall the plugin and start again. However, even deleting the files doesn't clear the settings and keys from WordPress as they are stored in the database. I'm kicking myself for not backing up before installing the plugin. I have tried manually deleting rows from wp-options (all the ones with option_name starting 'twp' or '_twp'. Is there anything else I should delete?