What was the first ARPANET message?

Detailed Solution:

"The message text was the word login; the l and the o letters were transmitted, but the system then crashed. Hence, the literal first message over the ARPANET was lo. About an hour later, having recovered from the crash, the SDS Sigma 7 computer effected a full login" (Wikipedia article on Arpanet, accessed 12-26-2012).