What are the possible causes for getting the "You do not have sufficient permissions to access this page." message when logged in as admin? I've done a lot of searching and found a lot of possible solutions, but in my case they haven't worked.
In my case I've taken a copy of a database off our staging site (close enough to having the same code) and placed it on dev, done the usual steps of changing values in the options table, gone to the lengths of disabling all plugins (through the database, even to the point of renaming the plugins folder). It was a multisite install at one stage (but this should have been cleaned up). I can log in, but get the access denied when I try and go to the dashboard page.