> Unknown logic "ZF" -- no heap file found in:
The Isabelle team stopped shipping a precompiled ZF heap some time ago.
You need to go to the Isabelle2011-1 directory where the build script is and run
./build ZF
That will build the FOL and ZF heaps. After that the Isabelle2011-1/heaps/polyml-5.4.0_x86-linux directory should contain FOL, HOL, Pure and ZF heaps. You may also want to change the line
ISABELLE_LOGIC=HOL
in Isabelle2011-1/etc/settings to
ISABELLE_LOGIC=ZF
Slawekk