I can't say what changed for him, but I just had the same occurance, though a bit different. I used my Movie Studio Platinum12.0 last night without any issues. This morning, while opening a new project, I received this error message "The playback device Microsoft Sound Mapper does not exist." I'm on Windows 10 with a new Dell XPS high end machine and NVIDIA card. I did nothing to change the default audio output and not used Sound Mapper before.
I did as one person suggested and went to Preferences>Audio Device> and changed it to the other only options available "Windows Classic Wave Driver" and "Direct Sound Surround Mapper". At least on the Windows Classic, my sound card populates the Default listings....but....I get the same error message, just with it's name in place of MS Sound Mapper!! And that locks up the whole project process.
I would suspect there was an update behind the scenes, either by MS or Dell and it has changed some setting somewhere....lord knows where...the reason I'm frustrated with MS and Dell all the time. (The "Should have got a Mac" ad keeps running thru my mind....)
I'll keep googling until I find an answer, but if anyone knows of one....HELP!!
The latest update I have is "Build 322". Does anyone know if this is the last one or is there a more recent one? I would like to obtain a copy of a more recent update if there is one. I have the legal serial number to use. This is NOT a pirated copy.
Environment: MS Windows 7 Pro 64-bit. Maybe some day I will be brave enough to go to Windows 10, but I prefer an OS without boxes.