Preview & Adobe Clearscan save file problem

Preview appears to have some compatibility issues with Adobe Clearscan OCR'd PDFs. While Preview can view and read the PDF initially and can copy text from the PDF into other applications; if you attempt to save the PDF in Preview (with or without making modifications), the subsequent document loses all of the scanned characters and copied text turns into a series of ␣s. As long as you do not save the file and simply open and close it in Preview, the characters remain intact. Additionally, the other OCR formats in Adobe do not generate PDFs that exhibit this bizarre behavior - they can be saved without loss of characters.

* Note - Clearscan PDFs were generated in Adobe Acrobat Pro 9.3 on a Windows XP x64 machine while the version of Preview used was 5.0.2 (504) on OSX 10.6.3.