We installed a program called Imaging 4.0. It allows us to view .tif and .tiff files in a special viewing way, which is very helpful. The default program to open .tif and .tiff files should be this program, but it appears there is something wrong with the name of the current default program. When we select Open with -> Choose Default Program, we specify the program "imaging.exe", which is the right program. Even though we select it, all .tif and .tiff files open in Microsoft Photo Viewer, which is wrong. If we switched it to say, Paint, it will open in Paint, but then we choose Imaging again and it goes back to Windows Photo Viewer. My guess is that somehow the name of the Microsoft Photo Viewer in the list of application to choose from when selecting what application to open it by default, is the same as the Imaging program. This would make Windows 7 think it has to open it in Photo Viewer instead of looking at the .exe file location.