Menu type Horizontal generates plenty of ERRORs:

Strict Standards: Only variables should be assigned by reference in .../modules/mod_foldermenu/mod_foldermenu.php on line 14

Strict Standards: Non-static method modFolderMenuHelper::getMenus() should not be called statically in .../modules/mod_foldermenu/mod_foldermenu.php on line 19

Strict Standards: Non-static method JSite::getMenu() should not be called statically in .../modules/mod_foldermenu/helper.php on line 19

Strict Standards: Non-static method JApplication::getMenu() should not be called statically in .../includes/application.php on line 593

Strict Standards: Only variables should be assigned by reference in .../modules/mod_foldermenu/helper.php on line 19

Strict Standards: Non-static method modFolderMenuHelper::getMenuXML() should not be called statically in .../modules/mod_foldermenu/helper.php on line 124

Strict Standards: Only variables should be assigned by reference in .../modules/mod_foldermenu/helper.php on line 138

Strict Standards: Non-static method modFolderMenuHelper::getMenuXML() should not be called statically in .../modules/mod_foldermenu/helper.php on line 169

Strict Standards: Only variables should be assigned by reference in .../modules/mod_foldermenu/helper.php on line 138

Strict Standards: Only variables should be assigned by reference in .../modules/mod_foldermenu/helper.php on line 125

Strict Standards: Non-static method modFolderMenuHelper::writeinXML() should not be called statically in .../modules/mod_foldermenu/mod_foldermenu.php on line 20

Strict Standards: Non-static method modFolderMenuHelper::getMenus() should not be called statically in .../modules/mod_foldermenu/helper.php on line 184

Strict Standards: Non-static method JSite::getMenu() should not be called statically in .../modules/mod_foldermenu/helper.php on line 19

Strict Standards: Non-static method JApplication::getMenu() should not be called statically in .../includes/application.php on line 593

Strict Standards: Only variables should be assigned by reference in .../modules/mod_foldermenu/helper.php on line 19

Strict Standards: Non-static method modFolderMenuHelper::getMenuXML() should not be called statically in .../modules/mod_foldermenu/helper.php on line 124

Strict Standards: Only variables should be assigned by reference in .../modules/mod_foldermenu/helper.php on line 138

Strict Standards: Non-static method modFolderMenuHelper::getMenuXML() should not be called statically in .../modules/mod_foldermenu/helper.php on line 169

Strict Standards: Only variables should be assigned by reference in .../modules/mod_foldermenu/helper.php on line 138

Strict Standards: Only variables should be assigned by reference in .../modules/mod_foldermenu/helper.php on line 125

Strict Standards: Only variables should be assigned by reference in .../modules/mod_foldermenu/helper.php on line 185

Dear Andrzej,

Please go to your Joomla administration panel, then Site->Global Configuration, then go to Server tab and in the Server Settings section change the Error Reporting from whatever value it has to Simple.

Go to the Server tab and change the error report from any value in the Server Settings section to Simple.