There is no software on this planet that has no bugs and if an application behaves irrational there is a good chance that your have just found one. But there also can be another cause: The application package could have become damaged, for example during an update or through a bug in a totally unrelated piece of software on your computer.
If something happens like this:
then please try to trash the application package. Then empty your web brower's cache, download the software in question again, and re-install it. In many cases this cures the problem.
If this does not help try deleting DEVONsphere Express' preferences files located in '~/Library/Preferences' and starting with 'com.devon-technologies.sphereexpress'. Visit the Go menu in the Finder with the Option key held to access your Library folder.