I figured out that the ‘shadowy’ background is the result of the previous image’s painted in state revealing itself in the onion skinned shadow image.
Opened Toon Boom 5.0 after 5 days. My work (line drawings painted in) had (1) a colored (light blue-ish) shadow behind the images; (2) images on screen seemed to be tiled in some way. For instance, if I chose to enlarge the image, only one tile enlarged with the rest of the image remaining the same; (3) Toon Boom not responding as I expected: I selected contour editor, clicked on the mouth of image and the contours (lines) of the nose highlighted instead of the mouth. There are several other erratic responses as well.
Anyone having such erratic behavior? I am on an Intel Core Quad Q8200, 4 GB memory, with a 64-bit Operating System. AND I didn’t have these problems last week.
Thanks 
Why wait for an answer when I can figure it out myself (sometimes). So, I had created the original animation in TBS 4.5. I created a copy and saved it in 5.0 (to my desktop). When I opened up the version this morning I opened up the 4.5 version and attempted to make edits. Hence all of the glitchy responses.
The 5.0 version is fine and I am able to edit without a problem at this point. I’m keeping my fingers crossed.
don’t know why I’m unable to make changes to 4.5 version and save as 5.0 version but it won’t let me. So I had to make a copy save it as 5.0 and then edit. OK then.