Great, thanks very much for doing that, and no don't be concerned that you are causing me problems, you are helping me.
If I have written routines to do basic things like save an image, I need to know that they will work as they are supposed to, and if not, find out why, and fix the issue.
I really should have a bunch of VMs set up running different versions of windows so I can test things out to make sure that they are work in all environments, but at the moment I am limited to just my main machine, which remains, as it has been for many years, a 32 bit XP installation. So until told otherwise I can only assume that when things work on that that they will work everywhere else.
So just making sure I have this right: you have tried with 2 different systems, both running win7, both fail to save a .png image, and you have now ruled out your monitor/desktop configuration as a factor? Also using the original version that saves to .BMP you have, at lest some of the time, had glitchy SSs saved that are not constructed correctly on both systems?