Q: I've used different programs to view JPEG photos on my Windows 10 PC. To do that, I periodically changed which program I wanted to be the default photo viewer, switching from Microsoft Office 2010 to Adobe Photoshop Elements to Microsoft Paint. Now I want to switch back to Office 2010, but Windows 10 won't let me so I'm stuck using Paint. What can I do?
Craig Wiester, Minneapolis
A: You have run into a Microsoft technical change that has had an unintended effect.
Beginning with Office 2010, Microsoft decided to speed up downloads of Office and Office updates by using "click-to-run" technology that treated software downloads like streaming video. Just as you can start watching a streaming video before it's completely downloaded, you could start using Office 2010 before the entire program finished downloading.
To make this downloading system work, Microsoft isolated Office 2010 from the rest of Windows by putting it in a "virtual environment," a self-contained bubble inside of Windows.
This bubble is the source of your problem. When you first opened photos using Office 2010, you probably made the included photo program, Picture Manager, your default JPEG viewer. But, because Office lives in a bubble, it didn't communicate that to Windows 10.
Then you used the Windows desktop to open photos, first in Photoshop Elements and then in Paint, and told Windows to make each of those programs in turn your default JPEG-viewing program. Windows 10 could do that because both those programs are outside the Office bubble.
Now you want to switch back to Picture Manager. But it's inside the bubble, so Windows doesn't know you have selected it as your default photo viewer. As a result, Windows continues to open JPEG photos in Paint.