Hi @puzzlezaddict, I tried the takeown command in both accounts, but still got the game already running error.
However, I also manually updated my graphics card driver, and right now the game is working. I was able to launch and exit a couple of times in a row. If it does not work again tomorrow, I will be back.
If it keeps working, I would like to thank you very very much for taking the time to help me with this issue!!! I really appreciate it. Now I can go and build my silly little houses again in my silly little free time. 🙂