Bug 114648 export file system/archive wizard initally has error when no selection seeded
Make sure nothing is selected in your Navigator or Package Explorer. File > Import/Export Select Archive or File System BUG: there is initially an error - There are no resources currently selected for export. There should not initially be an error in these wizards.
bundles/org.eclipse.ui.ide/extensions/org/eclipse/ui/dialogs/WizardExportResourcesPage.java
int separatorIndex = resourceName.lastIndexOf("."); 
        if (separatorIndex == -1)
            return false;
        String extension = resourceName.substring(separatorIndex + 1);
        Iterator it = selectedTypes.iterator();
        while (it.hasNext()) {
            if (extension.equalsIgnoreCase((String) it.next()))
                return true;
        }
        return false;
    }
    /**
     * Persists additional setting that are to be restored in the next instance of
     * this page.
     * <p> 
     * The <code>WizardImportPage</code> implementation of this method does
     * nothing. Subclasses may extend to persist additional settings.
     * </p>
     */
    protected void internalSaveWidgetValues() {
    }
    /**
     * Queries the user for the resource types that are to be exported and returns
     * these types as an array.
     *
     * @return the resource types selected for export (element type: 
     *   <code>String</code>), or <code>null</code> if the user canceled the 
     *   selection
     */
    protected Object[] queryResourceTypesToExport() {