[PLUG] Odd display of .pdf in Firefox on Ubuntu 14.04

[Dick Steffens]

I have an internal website with a pair of .pdf files. One is in color, 
the other is the same thing in black and white. They were both made from 
a .jpg. The web page has links to these two .pdf files. When I click on 
the b&w one Firefox opens it and it looks correct. When I click on the 
color one, Firefox opens it, but it looks weird. It's black and white, 
but there are repeating images in the background, it's really dark, and 
only the top 1/4 displays. If I open it with the Midori browser (same 
Ubuntu 14.04 machine) it looks correct. If I open it with Firefox from 
an Ubuntu 12.04 machine in the house it looks correct. If I open it with 
Firefox on Linux Mint it looks okay. If I open the .pdf file with 
Document Viewer on my Ubuntu 14.04 machine it looks correct.

So, the only place it looks weird is with Firefox on Ubuntu 14.04.

What should I be looking for to figure out why this looks strange?

Thanks.

-- 
Regards,

Dick Steffens