I've got the regular edition on CDs...everything has worked normally up until now.

I linked to Noloben, went rummaging around, dropped the slate before making it rain (duh...) to go up the ladder...my slate disappeared and was no where to be found. I regressed to a past save and tried again.

This time my slate showed back up after I did the whole rain thing (first, I'm not stupid enough to try it a second time). But now, after getting the Lab symbol to show up on the slate itself, it still won't show up on the pedestal. Um...I need it to in order to continue the game.

This time, regressing to a previous save only made my slate disappear once again. So, now what?

Hi Kehra,
If you drop the slate without anything on it, the Bahro will take it back to the first bubble in that age. As far as the first pedestal in the lab, after you put the symbol on the slate, put it on the pedestal. Once it is on the pedestal the symbol should show up on the first pedestal in the bubble. Check the first pedestal to be sure before continuing. I hope that helps.

The problem was, the Bahro wasn't taking it back to the first pedestal, or the one in Direbo. It's possible if I had stayed to watch it might have been put back, but since I went up the ladder, I couldn't see. It was just gone.

As for the other issue, yeah I guess that one was a user problem. >.>

If nothing else helps, try re-installing EoA from a clean boot. See Myst V: Clean Boot Install/Re-install With Win XP, one of the stickied topics at the top of this Forum.