If you compile your applications on JDK7 you have to run Apache TomEE 1.0 on jdk7
If you have multiple JDK installed on your system you should set JAVA_HOME in your stratup scripts.
For example if your JAVA_HOME is /usr/local/java/current edit catalina.sh
and add a line
JAVA_HOME=/usr/local/java/current/bin
Alternatively, set JAVA_HOME as an environment variable prior to calling <tomee-home>/bin/startup.sh
TomEE 1.0 package comes with and "endorsed" direcotry which contains updates for core JDK6 libraries. If you are running JDK7 you should remove al files in this directory.
TomEE 1.1 will detect JDK7 and will not load those files