Klaus,With the quick help of Steve from Scitechsoft, it seems that the first problem (that only one of the monitors is being turned off) is a bug of SNAP. He checked that both monitors are turned off with a Matrox card, but the second monitor have problems with an ATI Radeon card.
You might also be able to check it, by running the gactrl.exe program in the SNAP folder, and doing the DPMS tests.
He also shed some light on what the SET SNAPHRES is good for. The result is that its presence or absence should *not* cause any hangs or crashes in PM programs. It only tells the system that the desktop width reported to user applications should be divided by a given number. (So they center their windows into the first monitor.)
So, if it still crashes without this SET, but does not with it, and it's a problem for you, I might create a debug version for you to track it down. In this case, please contact me directly in email.
Doodle