If you haven't already, go to Corel's website and find any service packs, updates and patches for you particular Corel product. Download and install them. See if that helps.
Hi, you must remember that CorelDRAW is a software of 1994, you can't use ir for a newest file format. You can open the PDF with Acrobat, and save as EPS, or import the PDF in a newest versions of CorelDRAW (x3, X4) and save as CMX 5.0 or an older version of CorelDRAW.