This is likely due to the limitations of your DVI viewer. The DVI file itself does not contain EPS files: just a link to these files. When DVI is converted to postscript (and from there to PDF or directly to PDF), EPS files are included. Some dvi viewing services included EPS files, others did not.
PDF, , EPS.
google , , YAP ( miktex) EPS , , ghostscript , , YAP, , DLL ghostscript.