Microsoft Word/Office 2007 - Unable to paste from body of document into "Document Properties" / "Document Information Panel" Fields

We've deployed Microsoft Office SharePoint Server 2007 and upgraded our clients to Office 2007. We've noticed something very strange and very concerning though...Word won't let users copy text from the document body and paste into any of the fields on the Document Information Panel. Interestingly, you can copy and paste text from the word document body into a notepad file and then copy the same text from the notepad file directly into word....any ideas on whether this a bug or how to configure word to get around this rather glaring limitation?