I was getting error messages (cannot delete folder "WEBNAME") for deleteweb operation for stsadm and when opening the web in SharePoint Designer (SD) I got "There is no web "/XXX/YYY". Couldn´t delete documents but the web was browsable in SD (error code 16388). I finally tried to attach to the database in Visual Studio and got an error message about full transaction logs on the database server. In this case we configured "simple mode" instead and all operations completed sucessfully.
So know your DBA and have them close :)