DX(G) pdf files don't display pictures or are blurred

My Kindle DX has a lot of pdf files but none of these display the pictures of screen shots very well or at all. It will display tables and code and flow chart style drawing such as OSI Stacks etc.
Is there a newer version of the viewer in DX? My version is 2.5.8 overall version.
thanks,

Mel
http://s.mobileread.com/i/smiliesadd1/help.gif