Why is my beer cloudy?

[Twopan]

I have had batches inexplicably refuse to clear, same recipe, same process, but one batch clears rapidly and another looks like pea soup after two weeks. It's happened a couple of times to a Malt Miller Leffe clone (all grain). I always add protofloc and brewbrite at the end of the boil but it's still inconsistent. I have found that being tempted to bung it it in the fridge after two weeks has no effect. The only thing that works is time. Leave the bottles in the shed/garage at cool, but not cold, temperatures for as long as it takes. My soupy Leffe eventually became as clear as a bell.