Thank you. After I executed the two commands you suggested in Post#2, I restarted Windows. A wallpaper showed up. As a test, I waited for five minutes before pressing the Return button. The white box to allow me to enter the password did not show up. Clicking mouse buttons did not help.
Then, I followed the steps in Post#4. This time, after seeing a human symbol (a circle on top of an inverted C), my userid and the message "Please wait for the User Profile Service" (which seemed to complete in a shorter period of time), the white box which allowed me to enter the password showed up by itself. Previously, I had to press the Return key or click a mouse button in a short period of time for it to show up. I logged in Windows successfully and the normal yellow cursor symbol appeared.
One thing I noticed is that I used a demo version of CursorFX to make the cursor bigger and fancier. However, the evaluation period has ended and I decided not to buy it until it is on Sale. When I restarted the PC, that bigger fancier cursor showed up. I also use Wallpaper Engine. Not sure if they are causing the problem.