I just upgraded to Microsoft Office XP, service pack 2 (SP2). Now when I double click on a structure to edit it in Word, I get, "This object is corrupt or is no longer available."
Microsoft's service pack unregistered ChemDraw in your registry. You will need to reregister it. Go to your Start menu and choose Run. In the text box that appears, type (or copy and paste) the following:
Click OK. You should now be able to edit ChemDraw structures embedded in Word. For more details, on this Microsoft bug, please see article Q328613 in Microsoft Knowledge Base: