I have the same issure as taxtwit, annoying that it happens so often.
OK, I had the problem taxwit and you have and now i don't have the problem. Or don't seem to.
I use to leave my 6100 on all the time and as you scrolled west for new shows the guide would soon have to download.
But my cat likes to sleep on the 6100 as it is warm. Been turning it off and the guide must download behind the scenes??? and I have to less download the guide it seems.
My 2 cents.. ( 2 cents american too ) not sure if this is a total fix but the 98% downloading seems to be not an issue now.