Combining a word file with a PDF - cant get rid of shading round the word part?

When I try to combine a PDF with a word (2003-2007) file, the page that used to be the word file appears to have a shading around it which I cant get rid of. I just want all pages of the document to appear the same. It is a four page document - the three from the original pdf look fine but the one converted from word has a shading round it like the page is hovering over some imaginary table with a shadow around the edge of it. Does anyone know how i can get rid of this effect?