August 27, 2006 9:32 PM

You might check the official support thread, as this has been discussed there several times.  In short, you could have a bad burn, a bad download, a picky CD-ROM drive... See below for links...

For answers to commonly asked questions, please refer to the
InstantCake Instructions and Release Notes,
Official InstantCake Discussion Thread, and the
Official PTVnet Discussion Thread