really weird bug-
My level 30 druid had just defeated all of Baal's minions, and I was picking up the magic crap left around the throne. there were two bucklers (both lame), but when I went to put them in my pack, they were invisible! I could see the spaces being taken up, but no buckler. Okay- no biggie, I'll just go to town anyway, before going after the big guy. Activate TP and step through to find the entire town is empty! no people, and no stash! whenever I walked through where the map showed a NP was, I would turn invisible, and after a couple of times doing this, I went invisible as well! Too weird. Now I'm thinking to myself, maybe Baal won't be able to see me either! So I go back and step through to the worldstone. I do my best but now the festering appendages are invisible, as are all of Baal's attacks. I died pretty quickly, since I couldn't see a damn thing, and just decided to call it quits and reboot. Luckily I hadn't left too much on the ground to be lost. BTW, this is all solo play on my laptop with 1.09.
Has this happened to anybody else?

I know sprites start do disappear when there's an ungodly number of sprites already on the screen (such as bloodsplatters, or the insane number of critters which is spawned when using the "-seed (number)" command line), but there's no reason for the sprites in Harrogath to disappear.

It's probably a glitch in the game's coding, and you might be able to fix it by switching video modes, by using the video test utility, located in your diablo 2 directory.

I've occasionally seen the people in towns dissapear. I've never seen myself or any items go invisable, though. What I would have done is hopped into a public game, and if you still couldn't see yourself, ask others if they can see you. The answer will probably be yes, but in the rare event of a no, then I would have never mentioned it except to Blizzard in hopes that lame PKers wouldn't figure it out.