When I using Zend Optimizer 1.3.1 with PHP 4.2.2 
PHP take to me Segmentation fault :(
Without Optimizer all work correct.

Compile line:                                      
./configure --prefix=/usr \           
    --with-config-file-path=/etc/php \
    --with-exec-dir=/usr/bin \        
    --with-mysql=/usr/local/mysql \   
    --with-curl \                     
    --enable-sockets                  

Backtrace:
(gdb) run                                           
Starting program: /usr/bin/php                      
                                                    
Program received signal SIGSEGV, Segmentation fault.
0x80f5e16 in zend_llist_apply_with_del ()           

(gdb) where
#0  0x80f5e16 in zend_llist_apply_with_del () 
#1  0x8167480 in cgi_sapi_module ()           
Cannot access memory at address 0x1.