What kind of grinder are you using? In our new shop I got two Mazzer Major E's, and they're fantastic. My other shop has a modded Super Jolly, and it does what you're describing. It's getting replaced in the next couple months.
Sounds like a Super Jolly to me, though there are plenty of others that do this. It seems to be worse as static rises in the winter months too.
The quickest and cheapest fix is to make a little chute out of an index card, file folder, or any other stiffer cardstock. Cut a 1-inch-ish wide strip a couple of inches long, roll it into a tube, and slide it up into the doser hole. The hole on the Super Jolly is sort of a squashed circle, so try to form the tube to match. Once you have a good fit, mark where the ends are, remove it, trim off excess length (you just need a little overlap), and tape it together. The goal is a tube that fits perfectly, is wide enough to stick up in the doser hole enough to stay in place, and hang down about a quarter inch. It may take some trial and error, but you should get something far better in a slow afternoon.
Hope that helps.
Agree with Brady, that's the cheapest fix for the problem. For a more professional option, you could get the Elvinator from Espresso Parts. http://www.espressoparts.com/ELVINATOR_V1?&search_id=1252620
I had a similar problem with a my Mahlkonig this summer. High humidity seemed to make pulling a good shot nearly impossible. I had to tamp so hard, my wrist hurt.