My exact problem. When I called Samsung, the CS Rep told me just Factory reset the phone and a fix will be out by the end of October... I told him if that's the case, I'll have an iPhone4 by the end of September...
When I left the store with the phone, it locked onto me instantly and stayed locked the whole way him. Since then (Thursday), not a single satellite lock. And it's actually pretty aggravating.
I'm hoping AT&T won't give me issues exchanging the phone (
I went through 3 Captivates this week - each had quite a few issues... shutoffs, no GPS, no update available, OS restarts... Yet the Sales Rep claimed I wrote on my account I used an exchange to another phone, not because my phone was defective - read: BRICKED). I think I will go for an iPhone4 and if these ever get properly fixed, sell it and buy a Captivate again. I love this phone but the issues are starting to really get to me.