I recently downloaded and installed IE 9 on my Win 7 x64 laptop (Thinkpad T400).
Editing documents in Sharepoint (rich HTML editor) results in the browser hanging (screen turns white, cursor to egg timer).
Tabbing between web page sometimes works, other times the tab changes but the web page that was tabbed to doesn't render on screen.
I did have the IE9 platform preview installed, which I've since uninstalled and rebooted the computer, and have also disabled all add-ons.
I'd be interested to know if anyone has experienced similar issues.