I went to open an older Encore DVD 1.5 project to find that it has developed a problem.
The small thumbnails at the beginning of clips in the timelines are garbled (they almost look like negative images). That, in itself, is no big deal but . . . all the video buttons also contain the same garbled look. I have Encore DVD 2.0 installed also, and I created a test project using the same video (.m2v) and same button and it works just fine.
I really don't have the time to re-build the entire DVD in 2.0.