It's a known bug with CB 1.1 and will be fixed very soon. Use zend optimizer 3.3.3 or update CB to 1.2 for now. Thank you.
Make sure all zend_extension lines are commented out, except:
zend_extension=/usr/local/lib/ZendOptimizer_5.2.so
"./build zend" does not build anything on Linux systems, just extracts the tarball and copies data/5_2_x_comp/ZendOptimizer.so to /usr/local/lib/ZendOptimizer_5.2.so.
CustomBuild 1.2 installs Zend Guard Loader for PHP 5.3.
CustomBuild 1.2 installs Zend Guard Loader for PHP 5.3.
It's broken for 5.3.5 for some reason... it worked for 5.3.4 though.