corrupt pdf when importing file- help needed

All my pdf's from my Epson V370 scanner are now showing up as "the file is corrupted" when I try to import them into CD X8. I can import other pdf's which are not scanned docs but just not my scanned ones. I can open up the Pdf's using Adobe Acrobat Reader and they are good documents. I have searched through the forum for an answer as well as on the CD X8 help pages.
The items I need to scan and process are for laser engraving and this issue is driving me nuts as it only started about a fortnight ago and I cant think of any reason why this should be happening.