Indeed it is a good collection of debugging for many of members like me,Also http://www.8052.com/forum/read.phtml?id=96577 can complete this thread,
I have experienced some of them myself And have inscribed in my mind,Specially Misc. Notes is very useful,I repeat some of them that i interested more
1).Never figure anything is working right until proven by repeated experiment
I have stricken from it once very awful
2).Most problems have simple causes and solutions
3).Problems that mysteriously go away tend to mysteriously come back unless you can prove that the change really fixed the problem
4).Stay focused on a single problem at a time.

Thanks again for sharing payman

Mehdi