Dell 720P: PDF - "Output file name" error

Hi, can anybody help with this problem, please?

 

I've set up my Dell printer and successfully printed test pages etc.  I began printing pages from a pdf document.  it worked.  but when i returned to the same document, to print another pages i was prompted by a pop up to type in an "Output file name".  I've tried just typing in a file name but this doesn't work.  All I get is an error message:

 

"could not start print job"

 

if i try to close this window, i'm then prompted with another pop up message:

 

Local Port: Could not open the file, the system could not find the path specified.

 

I've tried printing other file types and they work fine.

 

Any suggestions much appreciated!

 

Thanks