I've had this off and on for some time now. The occurance of it seems to be congruent with my mood, and I also experienced it more frequently (with more intensity) when I was drinking. A couple of notable experiences:
Once, a few years back I had a particularly vivid dream whereas I was in an apartment I used to live at in north TX. There was a party going on, and in the dream I met a girl. Within a few moments we were making out, and when I woke up, she was still in my arms, on top of me, kissing me. (For some reason I did not question the absurdity of the scenario and continued to kiss her). She then suddenly rose her head. Her face twisted into a demonic form very akin to the devil girls in the movie The Devil's Advocate. She then pinned me down and began to violently hump me while making some kind of loud, inhuman grunt, like a monstrous pig. I tried to scream but couldn't get anything out, much less move my body. Suddenly I snapped out of it and became "fully" conscious, and had the sensation that she instantly "slipped" under my bedsheets and into oblivion. I later read about the experience and discovered it was a phenomenon often refered to as "succubus". Needless to say, it scared the **** out of me.
Another time, I remember waking up on the living room couch. I couldn't move my body or speak, and remember thinking, "oh great, another bout of sleep paralysis". Usually I would thrash wildly in order to snap out of it. Sometimes it could take a very long time... anyway, at some point I remember my mom walking into the room, only she had a very bizarre, surreal movement about her... almost like stop-motion. I started to try to get her attention by calling out, but remember only getting out a low growling noise. She moved over and threw my dog on top of me (a chihuahua), and then promptly disappeared. I remember feeling my dog getting stuck under what I perceived to be my thrashing body, and fearing that I would crush him on accident, tried to get my hand to fall to the ground. It eventually worked, and when I snapped out of it I saw my dog sitting at the far end of the couch, looking at me puzzled, and my mom was still at work.
Strangely, some alcoholic friends I had at the time related similar incidents they would have off and on. One of them also had a panic disorder. My mom, who's also an alcoholic, has also experienced the paralysis, sometimes with the hallucinations involved. It appears to be fairly frequent with people with addictions and/or depression/anxiety issues, anyway.
Thanks for the link.