I am using 64bit 2.10.1-Pisa on Windows 10.
When I set up my composer to print, everything looks fine until I try to print or export. The composer goes completely blank and outputs a corrupted PDF using the Export to PDF function. The PDF file won't even open.
I had the same result exporting to PNG.
When I try to use the PDF document printer instead of exporting, QGIS stops responding indefinitely.