I was playing Demons's Souls this morning when my sound started to lag. It would skip and catch on parts of music, sounds wouldn't play at the right time. Nothing majorly annoying, until I entered 1-3. Every thing seemed totally normal at first (except the sounds), until I started walking a bit. I went through the large gate at the very beginning before fighting anything, and it still seemed okay. But as soon as I got near the first of the dogs, lots of things in my surroundings changed. Most of the light went out in certain spots, creating huge shadows. Weirdest of all was that the stone walkway on the ground disappeared and turned into a series of black squares layed over eachother. I walked back to the Tower Knight's archstone, and found the area pitch black. Since I couldn't see, I went back into the level. I was going to go rescue Yuriah the Witch. I ran past the fountain by the dogs and into the corridor found at right, leading to Yuriah. After I entered the gate which required the Bloody Iron Key, I found myself running THROUGH the wall in front of me. I fell through the floor and continued to fall for about 5 minutes with no sight of the level, now entirely above me, before I finally died.
After I respawned from this little adventure, I wanted to try again. I killed the dogs, but this time went left to continue the level towards the Penetrator. I found only one of the three guards at the top of the stairs, so I killed him. I stood around there for a few seconds, and the other two just appeared out of nowhere and started to attack me. I killed them, and ran through the gate which I had already opened from later in the level. I noticed that there were No More Enemies. At all. Then I fell through another invisible hole and died.
Let me know if you have ever had this problem, or if you have any comments or glitches of your own :)