[Plextalk] PRS and inverted folder order

I'm using the basic PRS software with Windows 7. I regularly use files from a particular folder to select and import into a daisy book. Until recently they were correctly alphabetically ordered. Now I find the order inverted and it has remained consistently like this. If I use Windows Explorer to look at the same folder it is correctly ordered. I cannot find anything in the PRS menus to correct this inverted order. Any ideas? BTW, this happened to me a couple years ago with a different folder. After several months it corrected itself. Needless to say, I do not know of anything I did to cause this. Thanks, Jeff