am new here and here is my story(sorry for bad english)
5 weeks ago,I was no-paranormal believer-but one night I fall asleep,and it was no ordinary sleep,I felt really cold,and then am in some gray room,I remember that I had a feeling that is not a dream,and I was very scared(I dont know why).and next I remember is a:somekind of ceramic mug-on my knee.
then I woke up-very cold,with sweat.and my left knee is hurting me almost everyday! When I told that to my mother-she told me that is a only dream...but am not sure-what do you think?

It was more than likely a dream.
Your subconscious created the mug at the spot you felt the discomfort because it started to feel that way before you started dreaming. The mug simply represents something your mind recalled that might give such a feeling when resting there.
What you are trying to do is interpret it from the reverse. Right?

not sure to understand you...CAN you be more specific?

What he means is that, as you were sleeping and dreaming, your knee was already hurting. Because you were sleeping, and because part of your mind KNEW there was pain in your knee, the pain was 'explained' in your dream as a mug.

For example, sometimes when my alarm clock rings while I'm sleeping, in my dream, I hear it ringing, but in my dream it is often a telephone.

Both the pain you feel and the clock ringing I hear are both messages to our brain. We are aware of these things, and thinking about or worrying about these things may cause us to wake up. So that we can continue sleeping and dreaming, our mind tries to put these things into our dream so that we will not be disturbed, so that we will not remember that we are dreaming and try to wake up

This is what he is saying.

This is only a theory, and probably SD is right.

There is one flaw Kirin. The subconscious has one law that has not been taken into account here. All of the subconscious activity is made of just one thing... What you do not already know...

It is fine for the cup and the knee thing SO LONG AS he does not know about the hurt knee. But once he does, the subconscious loses all power to use that against the person.

There is ALWAYS a factor unknown by the person for ALL subconscious activity. You can't reason with what you do not know. This is why the subconscious is so unreasonable in it's intrusions into a person's life. This factor may have nothing to do with reality. But it is still there none the less. If any subconscious influance returns, it is because there still remains an unknown factor. It may take secs, minutes, hours or years to find that there is something you were never aware of, but when you have it, that subconscious influance losses all power over you. This unknown factor will always be in your head where it is reeking havic along with everything you are aware of. It is never in the outside world.

But then again, that is something I believe. I don't remember seeing that in my psychology text books. So I am lableing it as such.

last night I had a same dream...but my left arm hurting me in dream..
like I get bited by a bee..but when I woke up I had no marks of bite on my arm ..

He could have ran his knee into the wall while sleeping if his bed is against the wall, or nightstand or?. In which case, if it did not wake him he gets his ensuing dream and...you know the rest.

no..I have a big bed..on a middle of room..no way of ran my knee in wall or something else..