To dream that you have a disorder or you are suffering from a disorder means that you have some kind of affliction which makes life more difficult for you. Likely this is some kind of disorder such as Down syndrome but in any case there is something going on with you that causes you to see the world differently, even when it comes to dreams.
If you have a dream in which you have a disorder or are diagnosed with a disorder than this means that you feel very different from others or that recently the differences between you and your peers have been highlighted to you in a harsh and no so forgiving way. If you have a dream where everything around you is in disorder or where a room that you always like to keep clean is in disorder this means that something has happened to you which has shaken all of your previously held thoughts and beliefs to the point where you are now confused and even more shaken than before.
One of the things it is important to note about a disorder is that seeing the world through different eyes is not necessarily a bad thing. Though we label people that suffer from mental disorders as special or retarded, this does not mean they are actually slow or less capable than anyone else, it merely means that their world view does not match up with the commonly held one. In other words, just because you see this dream meaning you see things differently does not mean that this is necessarily a bad thing. You should be totally fine assuming you still have a reasonable level of intelligence and you may even have a better quality of life than all those normal thinkers.