Well, tried again to resolve this problem. This time, I installed PCLinuxOS MiniMe and during the installation process, I disabled the ACPI functionality, during the Boot configuration step. After installation, went into PCLOS COntrol Center => System Services and made sure ACPI was Stopped. Once that was done, re-booted. Once system was re-booted, did a Shutdown. Now the system shuts down as it is supposed to.
Don't know why after flashing the BIOS of my MOB with the next to latest version should have resolved this problem, but it didn't. This should have resolved conflicts with ACPI, but it didn't. Nevertheless, I can live with ACPI being disabled on my desktop PC and very happy to be using PCLOS again as my favorite Linux dsitro. BTW, I have PCLOS installed on my HP laptop and I experience no problems with Shutdown on that device.
Well anyway, hope this helps others. And thanks to all who have helped me with this. I still think PCLOS is the best Linux distro out there.