I have compiled php with libmcrypt 2.2.6 (posix threads disabled) and zlib and mysql.
php is compiled as a module and used on apache 1.3.12
All works fine except when I use the mcrypt library.
mcrypt_get_block_size
mcrypt_create_iv
work fine, however calls to:
mcrypt_cbc
mcrypt_cfb
mcrypt_ecb
mcrypt_ofb
cause the process to crash, the following appears in the error log file:

Thu Apr 20 01:08:20 2000] [notice] child pid 21218 exit signal Segmentation fault (11)

I tried three different ciphers (on mcrypt_cbc) with the same result.