I have the unusual issue that certain pdf files that cannot be stored or opened without error, and crash the My Cloud drive and freeze Widows Explorer. I have to restart the computer and the pdf files have then disappeared from My Cloud Drive. It is only some pdf files form one source. These same pdf files can be stored and opened without issue on any other drives attached to my computer. The pdf files are from a reputable business source. Any advice or were to start looking for a resolution is appreciated please.