If a maximum heap size of 1.8GB or greater is entered in the ColdFusion MX Administrator's Java/JVM Settings page and the change is submitted, the user will receive a message stating the server must be restarted in order for the change to take effect. The attempt to restart the server will fail. This error has to do with the limitations of memory on 32-bit processor machines.
Maximum JVM Heap Size Greater Than 1.8GB will Prevent ColdFusion MX from Starting