Same problem. Excel 2007.
The only module loaded is "AcrobatPDFMaker (PDFMaker.xla)" and it's password protected. I can't check the status of this file but suspect its missing since a search doesn't fine it. I removed, using add/remove, PDFMaker using the Acrobat 8.0 Pro "repair/modify" option. I have no files in "c:\documents and settings\owner\application data\microsoft\excel" and "...\excel\xlsstart".
So, any ideas? It's not a show stoper but is just a pain since it happens every time I load or close Excel.
Thanks.