Firstly, you should really fill in your About Me section in your profile. I use that, believe it or not :P Night terrors can cause the evil presence sensation, among other recurring bad dream imagery.

Secondly, I want to say that while it may be tempting to call this a demon or spirit getting into your dream, I advise avoiding that answer unless all others are disproven (or the spirit one is absolutely proven, which would require acts of things like prophecy and whatnot...which is dangerous to get into if the case is that it IS something supernatural). So, presuming it's NOT a supernatural visit....

The evil presence (along with any negative characters in one's dream) are embodiments of your shadow self - the archetypal personification of your perceived flaws. Interesting that these flaws don't come out until something is fumbled on with an interaction. Are you putting on a facade to someone in your life? Are you trying to keep up a lie or a false face (like being someone at work that you aren't when you get home, say)? This evil presence could be the expression of distaste toward having to put on a face for different parts of the day, or whatever the facade might be. Whatever it is, though, it's something you haven't overcome yet and don't necessarily have the strength to overcome...otherwise when you went lucid you'd be able to out and out end the dream. That the subconscious holds you in dream mode tells me that the fear/distaste is so strong your mind is insisting on you facing it.

Just in case it IS supernatural, I'd like to offer you this, as well. I don't know what your religious/spiritual beliefs are, but I've lived as a pagan and as a Christian throughout my life (no, not simultaneously). Burning sage, and wafting it through your room, commanding any bad spirits/energies out (called "smudging") will clear your room; then line the perimiter with a stream of salt, and make sure you get the windows as well. That keeps them out. I've seen it work, and quite well at that. Some things are more powerful, and it's all faith based. The stronger your faith and moral fiber is, the more the being will have to fight. Regardless as to what it is...if you are Christian it HAS to obey the commands of Christ. All you have to do is pray that it be cast out, and cast it out with faith that God will protect you and the spirits must bend to its authority. Also have had to use this. It creates a fight but God always wins. Always. So if you face off with this dark presence, and it does something that convinces you it's not just part of your dream, but an outside force...just command it out in the name of Christ. The other methods still work even if you're Christian. I don't know why. I don't pretend to know. They just do.