I had a problem trying to auto-upgrade the twenty-ten theme from version 1.0 to 1.1. I repeatedly FTP’d to my 1and1.com webspace and deleted the .maintenance file from the WP root directory and tried again, but it never worked. Tech support at 1and1.com says that it’s a WordPress problem and I believe it now after seeing esmi’s suggestion above, ie renaming the plugins folder. I tried that and it upgraded in 2 sec’s the first time I tried it. Thanks esmi ??