Help!! System 7.0.1

[howang@durban.berkeley.edu (Hong Yun Wang)]

I am using an old Macintosh SE with system 6.0.8. 
I tried to install system 7.0.1 ( downloaded from ftp.support.apple.com )
and got the message "the installation was successful". But when I 
restart it, I got the message "system error: couldn't load MBDF".
Anybody there knows what is wrong and how can I fix it ?

Also I need to install the CommToolBox on system 6.0.8.
The instruction tells me to drop everything on the system folder and 
they will be automatically placed in the extensions folder. It didn't work.
These files did not go to the extensions folder automatically and when I
tried to open the application which requires CommToolBox, I got the
message "No CommToolBox". I manually moved them to the extensions folder. It
didn't work either.
Anybody knows how to install the CommToolBox on system 6.0.8 ?

Thanks for any help. Please e-mail me (howang@math.berkeley.edu)