List does not exist The page you selected contains a list that does not exist. It may have been deleted by another user.
I've seen this error in numerous sites. It seems to be related with the installation of SP1. Although this isn't confirmed, it appears that sites created before the upgrade to SP1 will exhibit this behaviour after SP1 is installed. Sites created afterwards will have no problem.
I couldn't find much more information about this error, nor any specific hot fix that addresses it.
The solution is to deactivate the Office SharePoint Server Publishing Infrastructure site collection feature and then activate it again.
Another more laborious solution is to create a new site collection, export the content from the old site collection and import it into the new one.