Please never downgrade to older versions
Once you have upgraded to a newer version, installing an older version to downgrade may cause irreversible data corruption. We'll explicitly block this in a future release, but for now please avoid doing this.
If a new version you upgraded to has issues, let's try to resolve the issues. Going back in version usually cases more problems. If you must do that, you will probably have to delete all data on your computer and resync the account from remote server.
Good to know about blocking on the betas
I thought I would give version 2 a try on a different machine because I really like version 1 on my Macbook, but unfortunately I'll be going back to version 1 because of what I consider to be deal breaker problems. I know it is just a beta release, but here are Just a few of the issues:
1. Many of the version 1 color schemes are missing, including the excellent Yahoo theme! In most of the remaining themes, the tab text is virtually unreadable.
2. Where did all the preferences go? When I click preferences all I see is the global page to select colors.
3. Version 2 takes almost 30 seconds longer to load on my brand new Core i7 iMac than version 1 takes on my old Core Duo Macbook.