Just bought the Cyan Worlds offer this weekend and am very surprised - none of my previous GOG purchases have caused issues, but realMyst and Riven are not behaving correctly. With Riven:

a) Simply moving the mouse to the top of the screen does not reveal any menu options, as referred to in a "SOLVED" post for a similar question.
b) Pressing "ALT" -does- reveal a menu, on which I have a tested a few things like setup and credits, which work normally.
c) Saving, either with CTRL-S (as stated in the manual) or by pressing "ALT", causes Riven to close entirely and return to the desktop.

I am running Windows 7 32 bit and have installed Riven to the default location - I notice that previous posters here and elsewhere on the web have indicated that installing any where else can itself cause a problem.

Any suggestions on how I can prevent Riven crashing?

Rant mode ON:
And no - I'm NOT wasting time going down the Virtual / Windows 98 route - it's SUPPOSED to be made to work with WIndows 7, else GOG have no business selling it as W 7 compatible.
Rant mode OFF

I was having the same problem (on WinXP). This is what I did, I renamed the original directory (Riven.Old). To be on the safe side I did copy everything into a directory called Riven. Starting the program from Riven directory continued to crash upon save or even attempting to open a save. Starting the program from the Riven.old directory allowed me to open a save and even actually save.

Try copying the entire program into a new directory, not sure if you really need to leave the old one or not. And run it from the new directory.

From that "SOLVED" post:

"Move the mouse cursor to the top of the screen and click there."

I was just pointint out that moving the cursor to the top of the screen does bring up the menu, but you have to left click once when the cursor is up there.