One of the bugs I recently found in your project is that if you enter the same name in two or more categories,there is no "error message" shown...For example,if you enter a name like "Doctor_Friday_22_11_2011" in a category and then type it again the same way,no "error message" will be shown like it should be...So,multiple categories have the same name which is not correct...
Hope I helped you...;-)