Must say I got the K750i on release date from Orange and there were alot of bugs, I feel they should have delayed the release by a week or so to get the software right.
This is what Vodafone did and my Step Dad has never had a problem with his on Voda.
I have a W800 and had no problems with that, just think it was Orange / o2's stock that had the main problems.
Great phone though non the less