Hi Elizabeth,
Try running them through the Check Item preview, it should provide more details on the 240 error. Ebay tends to group all new errors under the 240 header, and provide better details in the longer error descriptions. On any Item that fails submission or listing that fails revision, it should also be saved with that Item/Listing. Make sure the Item/Listing right sidebar is expanded and it should show you more of the error message.
More details should also be in the program event log. If you need help tracking down the details, open a support ticket and our team can remote connect to diagnose the issue.
John Manning, Senior Developer