In Windows Live Mail, I exported messages, and when I changed computers I went to the portable drive where I had exported the folders to & imported folders to, live mail & everything appeared in Live mail on Windows 8. Several days later I went  to one of the imported folders , and found the folder was empty. I started opening a number of the imported folders, to find they were all empty. Since by then I went back to the usb hard drive that I had exported to and found they too were empty. I've now lost several years of messages that I wanted to keep. What gives????