Can not update apps; asked to log on to different account
Since upgrading to Mountain Lion 10.8.2, among other annoying bugs, one is that when I try to update software on the Mac App Store, it says that I need to log on with the account I used to buy/install the software in the first place.
I only have and use one and the same account to buy and update software on the Mac App Store, and so there is a problem with Mountain Lion and/or Apple's databases. How can I fix this so that I can update my software without having to manually remove all traces of it, and then reinstalling the new version?
Thanks
MacBook Pro (13-inch Mid 2009), OS X Mountain Lion (10.8.2)