Thank you for your post.
I don't see the rest of your screen, so I am unable to tell if Manage Database is the active window. For example, if I click on the Finder, the Manage Database window will look identically to yours with only Create, Cancel, OK highlighted, and the top of the window being grayed out.
What you describe sounds pretty similar to this bug report: Bug in 11: Cannot realign/distribute/resize table occurrences
Is it the same?
This is one of many acknowledged bugs that can be found in the Known Bug List here in the Report an Issue section of the forum.
It can also be downloaded as a database file from: http://www.4shared.com/file/8orL8apk/FMP_Bugs.html