Try this. Open the file (d3d8.dll) in notepad and copy the entire contents with ctrl+c. It won't be pretty but it works. Now go to this website
http://www.miraclesalad.com/webtools/md5.php and paste in the data.
It should generate the following MD5 hash if the file is intact:
8ffb91e491e1af076ed455b3a62d35b2