|"Thanks for your help. I had a look through and nothing was missing. It was all in Times New Roman"|
Now I'm confused. In your first post you said the error referred to "Arial Narrow" not "Times New Roman"???
Times New Roman is a standard, default Windows font, whereas Arial Narrow is not even installed with Windows.
Most likely Adobe Reader has chosen to display the PDF document in the default Times New Roman font as a substitute, as I explained in my first post.
"Still unsure why this error thing happened though"
I'll attempt to explain as clearly as I can:
The creator of the document used Arial Narrow but did not embed that font when he/she saved the document. Embedding the font that was used would have avoided the missing font error and would therefore have avoided font-substitution.
Embedding the font ensures that the document looks exactly the same on any computer display, even where that particular font is not installed.