Apple Logic Pro /LogicExpress Discussion

Greetings to All,
I am having a problem with using the replace function that is on the 
transport bar.
It no longer removes audio when I punch in on a track that contains 
previous audio. This is something I have done from my endless trouble 
shooting of L7(a huge disappointment in my opinion).
I have searched all the preferences and could find nothing relating to 
this feature, anyone here know the source of this problem?
Also I have never been able to audition audio files I try to load from 
the audio window since installation of L7.
I only have MOTU hardware other than the G4s own I/O. I have tried 
various audition channels and nothing seems to work. Any hints?
Oh, one other thing , okay I'm sorry I don't mean to be a big burden 
here, I have been using Logic since ATARI Creator and usually can find 
the answers or workarounds  to most of the problems I encounter, but 
Logic crashes after I close a song every time, not to mention the 
various other crashes I have experience on a daily basis.
Actually I might compare my current version of Logic to a barn, as we 
have a lot of those old barns down south that have been abandoned with 
rusty metal roofs and missing siding, kinda leaning to one side, Oh 
wait I think I could probably fix one of those so never mind the 
comparison.
Anyways, I enjoy reading all the posts here and my thanks to everyone 
who presents useful info, just sorry I can't be one of those at this 
point.

kind regards,
Alan Hayes
Memphis,Tn.