Hi,
are you using PHP 5.3.0 which is shipped with Snow Leopard? The ionCube loader needed for Snow Leopard's 64bit PHP 5.3 is currently version 3.3.9.
ionCube's PHP 5.3 compatible loader (v3.3.9) contains a bug in exception handling which causes PHP 5.3 to crash. This is most likely your problem. We've informed ionCube about the issue and they are looking into it.
myDBR will however go through the installation if no errors are found in the environment check. So you should be able to fix the problem quite easily. Most likely cause for the install process to raise the exception is that the file permissions are incorrectly set. Make sure that the all the items in myDBR folder are owned my the Apache-user (_www by default in MacOS X). You can change the ownership via the Finder or from the command line.
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myDBR Team