Originally Posted by falko
Recompiling zlib won't break anything. Just do it!
OK, I did it. Did not work. So recompiling zlib with shared libraries is not the issue.
I went back to this thread you recommended
and followed instructions by gbjbaanb except I was installing on Breezy Badger (Ubuntu) so did not need to install ssl-devel. Worked perfectly except that I did not write down the correct pwd for MySQL so had to reinstall. [Insert appropriate rough language here...][Lots of it.]
This time I didn't recompile zlib so I could check if the shared libraries were the issue. Just used the tweaks in the link above. ISPConfig installed without a hitch.
I suspect the compiler gives the "recompile with -FPIC" message because it can't find the shared libraries. When you change the ./configure to "--with-openssl" and the MySQL symbolic links, the compiler can find everything it needs.
Thanks to everyone for the help and various links. And thanks to Falko and Till for a most impressive product.