Hi Sean, thanks for your response. I can't make out what is happening. I have uninstalled the original installation,downloaded again from the official site and installed MWSnap300 in compatibility mode XP SP2. MWSnap still behaves the same way - as soon as I click on the "Snap" button everything that was behind MWSnap is magnified. I think I'll have to look around for another similar app that functions OK.
The only other item of interest is that when I install MWSnap under compatibility mode XP, I repeatedly receive an error message indicating "Archive is Corrupted" when I attempt to uninstall it. The only way I have found to uninstall it is to install it again without a compatibility mode and then uninstall it.