Comment 1 for bug 1723367

All I've managed to find so far by scouring logs is that bazaar.launchpad.net is asking login.launchpad.net whether the OpenID signature is valid, and login.launchpad.net is saying no. But it's not failing for you on every request, just enough to break things. This is very odd.

Things to try:

 * Explicitly log out of both the code browsing frontend and SSO (there are a few different ways to log out, and I don't know exactly what you did): https://bazaar.launchpad.net/+logout and https://login.launchpad.net/+logout
 * Use an alternative browser (ideally one that uses a different rendering engine, if you can) and see if you get the same symptoms

It may yet be a problem on our side, but at the moment this is baffling so it's worth trying a few simple things first.