We've had the same issue, so thank you a lot for posting this as it helped us a tremendous amount.
I think what happens is: you supply more than one signal at a time and the interrupt does a check for all signals on the line.
Thus, if you have a request for iron ore, copper ore, stone and coal it ...

So when you launch a rocket (or enable it from the getgo when you make a new game) you're able to line up a few researches in advance. I think it would be awesome if you were allowed to change the research order in the queue by just dragging it around. Currently you need to cancel all queued up ...