I'd start by right-clicking on the package and click "Reset Package Hash". The full message you're getting is likey "Failed to download and hash all additional files", and since it download the file it's likely the hash that is incorrect for the file. This can happen if you change the batch file after the package has been scheduled.
It's also possible that it failed to download the taskmanifest file for the package. Check the sdclient_task##.log in the ldclient\data directory on the client, it should show which file failed.
Finally, more info on the message can be found here: http://community.landesk.com/support/docs/DOC-8224
thanks for your reply.
After checking the logs in the Doc file you gave I found a error message where the computer was trying to connect to a the core server at 10.x.x.x and that was not the ip of my core.
I have a second nic card with that address in my core that is used for the san backup. It is not supposed to be registered in DNS but it was.
To fix it I had to delete the entry in DNS and uncheck the box, "register in dns" in the nic settings.