This sounds like you plotted a course with a partial tank of fuel and used fasted course plotting.
You then you filled up and the ship is now weighted down with more tons of fuel limiting your jump range and it is spazzing out cause you plotted a course, but now you are too heavy to make the jump, and one of the jumps was at the limit of the light weight, but too far for the filled weight.
You then you filled up and the ship is now weighted down with more tons of fuel limiting your jump range and it is spazzing out cause you plotted a course, but now you are too heavy to make the jump, and one of the jumps was at the limit of the light weight, but too far for the filled weight.