I don't have my setup here, but I believe that
zlib1.dll would normally be installed into the Pan directory. Is
it present?
Either way, it is worth searching the entire C: drive to
see if you have any other zlib*.dll files present. If there is
a different version and it comes earlier in the search path
than the Pan one, that may cause issues.
I'll endeavour to take a look at this at home tonight. If
this problem persists, I might be able to do a Pan build with
zlib statically linked in.
Regards,
Steve