BTW, I deleted your other copy of this topic.
First of all,
do not put preference files ( or anything else you might want to restore ) in the Trash! Just put them anywhere except where they normally reside, a folder on the desktop is great. The reason is, some programs may not even open if you remove the wrong preference file. If you put them in the Trash, you are only one step away from losing them. If you put them anywhere else, you can always restore them to their proper place. If things work normally after removing them,
then put them in the Trash and empty it.
Secondly, in answer to your question about "trashing ALL of the computer's preferences", don't do that.
You may find that nothing untoward happens but I wouldn't bet on it. And the only way to restore
some prefs may be to reinstall the app or even the OS! If all
does go well, you will simply have forced every app and the OS to recreate new pref files, most of which will simply be duplicates of what you threw away. There is usually nothing wrong with 99.9% of your pref files and often none at all, so the exercise is a waste of time and flirting with extra work or worse. If you're concerned that a pref file may be corrupt, it is much safer to use a utility that can inspect them and maybe repair them. That's easy in X, as they are all simple, XML text files, have no info about 9.