Err, sorry. I guess I should call it a mission log.
Anyway, when you get to a point in a mission where you must travel to another system on your own, the mission log does not reflect this instruction. So if you gloss over the dialog text, sometimes you have no clue what to do next because the mission log simply says the same thing it says when you first got the mission instead of telling you "Go to the BBQKitten System".
Thus from there your choices are: alt-tab out of the game and look up the mission on Google, drop the quest and do it over again (being more careful to read all dialog this time), or simply drop the quest.