Little thing. Tutorials PDF on http://www.pixologic.com/zbrush/downloadcenter/ seems to be damaged. I have downloaded that file 10 times always with same result:
ZBrush_tutorials.pdf.zip: Unexpected end of archive
Anyone can check it?
Ah…I didn’t read that correctly. Similar result after I download it.
Yep, same thing here! 
I believe that those files are the same ones that are in the ZBrush 4.0\Documentation folder.
thanks for reporting, will be fixed shortly.