Import into Joomla! fails and causes system to log out.

We have installed civicrm in Joomla! and are attempting to import a simple cvs file. On the final step of the import, after the preview, the system fails and forces me to sign into Joomla! again. No data is imported. It appears that this is a permissions problem with the final importing php script, but I do not know how or where to fix this.