Orange San Francisco Freezes on Startup

[thinkfast]

Hi, as you can probably see this is my first post.
About 20 days ago I purchased an Orange San Francisco and I general I have been very pleased with it.
However about 50% of the time when I turn it on the screen freezes on the green robot logo. It stays like this and I am unable to get onto the phone unless I plug it into the charger and restart it. Presumably taking the battery out would have the same effect although I have not done this. I have not done anything to the phone like root it or unlocked it. There is a fairly standard bunch of apps installed on it and this problem has been there since I bought the phone.
Does anybody know or have any suggestions on how to fix this? As I have only just bought it I will take it into the shop if nobody comes up with a solution.
Thanks a lot if anybody can help.

 

[master_yoda]

Try a factory reset and see if it fixes the problem. If it fixes the problem but it returns later after installing your apps, its then most one of the apps causing it.

If its still the same staright after a factory reset, its a trip to the orange shop im afraid.