First of all, check that you have the very last version of all components involved. This means a recent version of the DBMS, of the HTTP server, of PHP, of PEAR, and of the browser.
Force your browser to reload all files. Even if you have the last version of ERW, your browser could be caching old scripts. If you can, erase the cache altogether.
Then, check the logs. You should have the maximum level of logging enabled in your PHP configuration file (including logging of all warnings, i.e., error_reporting = E_ALL) and also the ERW logging set to the maximum level (i.e., $_ERW_logLevel=ERW_DEBUG;). Warnings about usage of undefined variables usually show that you have misdefined some customisation variables or hooks. In this case, try first to disable all custom hooks and scripts.