Budapest - Lewis Hamilton lost his F1 championship lead on Sunday after retiring from the Hungarian Grand Prix in only his second failure to score points this season.The McLaren driver had started the day 14 points clear of fellow Briton and team mate Jenson Button and 21 ahead of Red Bull drivers Mark Webber and Sebastian Vettel, but ended it four behind winner Webber."I was accelerating out of turn one when I felt a sudden vibration and then a loss of drive," Hamilton said in a team statement after pulling over on lap 24."I initially thought it was a driveshaft failure but it now appears that it was a gearbox problem."Team principal Martin Whitmarsh said Hamilton would probably have finished third otherwise.Hamilton's last previous retirement was in Spain in May, when he crashed out on the penultimate lap while in second place due to a wheel rim failure but was classified 14th."Actually, I may have had an issue with the gearbox from the very beginning of the race, when I initially feared I had a brake-related vibration," Hamilton added."Whatever, it's a bit of a shame because, as always, the guys had worked very, very hard all weekend, and I think we'd done more than enough in the race to get up to the front and score some decent points."It's a pity to have a fault at this stage in the year, but that's racing - when you push the car to the limit, these things can happen."The team now has a two-week summer shutdown before the last seven races of the season.Hamilton added: "We'll learn from this, and we'll just have to work even harder to make sure we don't have any further problems this year, and that we can catch back up to the frontrunners - which I'm certain we'll be able to do."Share your thoughts on the Hungarian Grand Prix here!