Your comments

Maybe because the bookshelf image is the same as one of the frames in the animation? But it did get renamed...
You're right - I deleted 0025 5 from the folder and ran it through the player. The bug is still there.
This shows the extra file that doesn't appear in the builder. I wonder if that's the bug? 
This is the animation with ten frames imported as png images. There is one image that looks like it shouldn't be there (It happened when I added an image accidentally that was already in the sequence, deleted and replaced it. 

Skul Walk zip
L = 640 - 110
T = 400 - 100
R = 640 + 110
B = 400 + 100

The object is anchored in the center-middle
This assumes that the top left corner is (0,0), as the measurement icon indicates
Thanks - it's a start, Inna :-) If the square in the center of the screen at (640, 400) were 100x100 and you wanted random movement 10 pixels in each direction, the element's anchor point could not be middle center, Is this correct? (No, wait...)
That's so great, Adeel! I will be in touch with you soon. Ted :-)
I can do that - will save ppl time figuring out the creation and conversion process. One drawback is that it just takes a lot of manual clicking to add 21 pngs into the builder. I can't imagine a longer animation or mini-movie how many clicks that would have! Many thanks to Charmaine who put me on the right track in the first place :-)
I wonder if there could be made available a selection of categorized sample demos to download that would provide examples of such items as counter functions, and more advanced (but commonly used) effects. A repository of zip files that can be downloaded and extracted into the 'Book' folder and run. That would be a lifesaver. I also spend hours figuring out how to do make things happen in Interactbuilder - so much trial and error learning.
If Adeel prefers, I can conduct an interview with him by email and write up a distinctive blog post - would save him some time from writing the whole thing. Just a suggestion because I am very curious about how they designed a successful app. too!