Having now had this problem installing the Oracle Warehouse Builder with version 11g and 10g I though it deserved a mention here in my blog. If the Repository Assistant is just vanishing around 87 / 88% percent and you can see a final entry of "I am in processLoadJavaToken" or under unix you may get a message from the assistent 'reposinst.sh' saying "Failures occurred during processing" this might be helpful to you.
What is going on is, that part of your xml code is corrupt in the database, but that is not apparent! All you need to do is go to your installation directory "ORACLE_HOME" and switch to rdbms/admin then de-install and re-install the xml code like this:
1. log in as sysdba ("export {SID}; sqlplus / as sysdba")
2. enter "@$ORACLE_HOME/rdbms/admin/rmxml" and press enter. Wait for it to finish.
3. enter "@$ORACLE_HOME/rdbms/admin/initxml" and press enter. Wait for it to finish.
4. exit
After that remove any repositories before re-running the assistant. Also remove any roles installed by OWB.
