Myst has a specific freezing point for me: always when I go to the clocktower and pull the lever inside. Without fail, it freezes and crashes. Anyone have a solution?

I get the same thing. I waited a few minutes and then it started up again. At times it takes 5 seconds to move a step. Between the mouse and arrow keys, I find that the arrow keys help make it more stable. But the freezing I hope has a fix. Did you try changing your display, I think this help a little, because I can move to other parts.

I'm also having this issue in the Library using that elevator for the tower. The first time it happened after about 10 minutes of play time, so I ran the game in Windows 98 compatibility mode which let me play for about 20 minutes before it froze. Not sure what to try now, would love any suggestions anyone might have!

I had the same problems as you describe with the GoG-version. I also have the original Myst cd, compatible with win 95/98. My solution was to run the original game in Virtual PC :p

Changing displaysettings might work though, as well as running the game in a different compatibillity or as admin, other than that, I was at a loss.

I think this problem is caused by the version of quicktime you have. Myst uses Quick time 4 so if you have a later edition than this you need to uninstall it and then download
Quicktime 4.
You can get it from http://www.oldversion.com/program.php?n=quicktime
I hope this helps.