I just enabled InnoDB on my  MySQL server and I’ve made the necessary changes into my.cnf. When I restarted the MySQL server I got the following error in the log:

InnoDB: The InnoDB memory heap is disabled

After  some checking I’ve found that I need to set the value of innodb_use_sys_malloc to 0. After I added  this entry innodb_use_sys_malloc =  0 into the my.cnf and restarted the MySQL Server the error was gone.

NOTE: More info here: www.innodb.com/doc/innodb_plugin-1.0-doc-A4.pdf (see page 38)