The only "fix" I've found so far (for my 9630) has been to do a battery pull, or as in my case, a simulated battery pull using the Quick Pull app. Then, my GPS will work for some time, before "going cold" again and being unable to get a fix for a very long time (never waited long enough to see how long, though) -- whether I'm outside or inside and the sky conditions seem completely irrelevant.