So, you installed the Gnome desktop and PCLinuxOS Tweak (a utility to tweak the Gnome desktop for PCLinuxOS) and were surprised that you were logged into Gnome?
A reinstall should never be your first choice as a fix.
In this case, the best choice would have been to log out and choose xfce from the sessions menu. The sessions menu lists the DEs available to be logged into. It makes switching between DEs at login easy. When you switch between DEs and log in, you will be asked if you want to make the new session the default. Choosing yes will make that DE the default. - This is more complicated to describe than to do.
Dear Neil ManBear,
I had had no idea I was installing the Gnome desktop. I believe it was carried along with something else I was installing and I did not realize what I was doing.
I did not think to adjust the sessions menu.
You can be sure that, when I install PCLOS again, I shall be doubly certain to carefully
investigate any dependencies which are installed with programs.
I do admit that these problems were my own fault. I am awaiting the release of the new PCLOS Phoenix disk from which I'll try again.
In conclusion, I believe that this discussion has gone far enough so I shall 'lock' it. Thanks to everyone who read this and contributed to my understanding of PCLOS.