I'm in the Sunken Temple and had solved the stone puzzle and gotten the water flowing and Nate 'n' Wilbur moving, but before getting Nate out had to save the game (real life calling). When I went back to this point the water is no longer flowing NOR can I make it flow again. Starting from a savegame at the very beginning of the Temple, I can NO LONGER GET THE stone puzzle to work. I have the correct solution but the door for Wilbur will not open.

I saw old posts elsewhere of this very same issue but no good responses. Has anyone here seen this and overcome it?

It's odd that it affects older savegames, but you're not alone with this, as some digging revealed. Unfortunately there seem to be no easy fix for this bug. As it affects older saves, I'd definitely refrain from saving once the bug appears, but use a savegame that wasn't affected yet. Before trying again, reboot your PC and use e.g. CCleaner to get rid of all temporary files. Maybe the bug is persistent in some cached files.

(Seems my response wasn't added to the thread so here is a paraphrase)

The issue resolved itself after I closed the game and left the machine alone for 20+ minutes. I suspect there is some caching in memory or temp files that aren't being cleaned up immediately upon a game load so it's using "old" data. Anyway all is good.