Oh, it's much worse than that- Link is the superclass
of Process.  I've done this a few times, porting code
from Digitalk applications to VisualWorks.  Link is a
handy name, but a dangerous one in this case.

Oddly enough, I believe it is possible to add an instance
variable to Object in VisualWorks- perhaps this is
also possible in Squeak.  The problem with redefining
Link is that the instance variables and class kind
( variable byte, etc ) probably got changed, hosing
the variable bindings in the methods for Process.
If the instance variables originally needed for Process
still were defined, perhaps you would survive that
change.

But of course the real issue is that you wanted to name
a NEW class Link, and that is a Modules & Namespaces
issue- we do not have either Modules or Namespaces yet.

les