"Error building Admin Menu" problem is related to Joomla 2.5 / 1.7 / 1.6, this is a Joomla core issue and affects different extensions during installation.
This can also happen if you have tried to install DJ-Catalog2 for Joomla 1.5 on Joomla 2.5 by error, and then installing the correct version for Joomla 2.5.
If this happened to you while installing DJ-Catalog2 extension follow this steps to fix it:
If this is a production site do the backup first. Use for example great Akeeba Backup extension.
- Uninstall DJ-Catalog2 component and all it's modules and plug-ins
- Use FTP client to remove all DJ-Catalog2-related language files:
- Log-in to phpMyAdmin, open your Joomla database and from _menu table delete all rows corresponding to DJ-Catalog2. Usually they are located at the end of _menu table.
- Install DJ-Catalog2 for Joomla! 2.5. / 1.7.