I was able to resolve this issue by replacing the following two files (below) with the ones provided in the promptengine_calendar.zip (available from Crystal Reports Development Department). Otherwise, you can email me if you need it, or if there is a place in this forum where I can upload it, just let me know.
C:\Program Files\Business Objects\Common\3.5\bin\prompt.dll
C:\Program Files\Business Objects\Common\3.5\crystalreportviewers115\prompting\js\promptengine_calendar.js
Crystal Reports developers are going to update the KB article to reflect this patch, but it may take a month or two before it is posted.
So, the pop-up calendar runtime issue is resolved now.