I don't know about other people, but I once accidentally tried instantiating an extension of a class from within the class that it was extending, and it would kill apache everytime. I don't think you're supposed to be allowed to do that. (To break it down, it looks like even though clean extends p101, you're calling clean from within p101)
Well my first question would be, do you really need to extend p101? It looks to me like they're two completely different beasts, ie, p101() intializes your classes and adds objects to a library, whereas clean() is meant for sanitizing strings/variables. When you extend a class in Object Oriented Programming it's generally so that the child class can use some method or property of the parent/super class in conjunction with new methods that it defines. If the two classes don't use any similar properties or methods, and in this case, don't even really do the same thing, there shouldn't be a need to create the child->parent relationship of an extended class.
Um, and I don't want to insult your intelligence because I'm sure you can keep up, but broken down for a three year old, I guess I would say something along the lines of.... well, spyke, that's a question you should be asking your mom.
Well, the plan is to start creating somekind of Framework thingy, where i wan't to use the class p101 as an umbrella, from where i can call every other class, and then i wan't it to be like, you class p101, class A and class B. Then i wan't it to be able to use functions from A in B it the plan is that everthing gets "called" through class p101..
It is still very much work in progress as i'm very fresh in the entire OOP world :)
Kind of a chained singleton. You still don't need to extend anything at this point though, since you'll be able to call clean a la
$pUmbrella = new p101(); $pUmbrella->clean->clean_var($szString);
You may want to consider if you need to include and instantiate EVERY object on every page, every time. It seems like I'm doing this a lot lately, I feel kind of like a registryvangelist, but check this noise out: Registry pattern and definitely The Singleton Design Pattern for PHP <-- the singleton and registry are two of the easiest OOP design patterns to implement, but that's not to say they lack any power, as you'll find scripts all the way up to the Zend Framework using them.