The folder <C:\Program Files\Microsoft Office 2007\Office12\XLSTART> is empty. The only Adobe product I have is Adobe Reader 8.0. I believe it updated recently, but don't percieve that as a problem. I run RegCure and RegEasy regularly and they appear to detect and "fix" 10s, if not 100s, of problems each time. I can't tell if one of them has removed something that pertains to this problem.
Thanks again for your responses. Maybe with your help I can zero in on the cause and find a fix. I still think reinstalling the ActiveX component CreateObject is the solution, but I haven't found a way to do that.