When I open a Word document containing ChemDraw structures, a big red "X" appears where theChemDraw structure used to be.

When I open a Word document containing ChemDraw structures, a big red "X" appears where the ChemDraw structure used to be.

This problem is not ChemDraw specific. It is a Microsoft issue. Microsoft support web site has a number of articles on the red X issue. Please see article Q162349 and article Q180095, for reasons why the problem might occur and how to possibly avoid it.

Basically, you will need to re-copy and paste or re-import the orginal graphic (structure) again.

ChemDraw 4.0 and above Windows users can double click on the red x in Word. This should open the missing structure in ChemDraw. Copy the structure in ChemDraw, close ChemDraw and paste the image over the red x.  This should restore the original image. The Microsoft articles also indicate that for Word 97 users, there is a free update (SR-1) that may solve the problem.

There have been other reports that allocating more memory to Word (Mac users only) may also solve the problem. Try allocating 20-30 MB of Preferred memory to Word. To do so, quit Word if it is running, click once on the Word application icon, choose Get Info from the File menu, and set the Preferred memory to 20000K in the Get Info dialog box.