Blackberry app world and apps not connecting to any form of internet?

[LittleLou]

I recently bought a Blackberry 8520 curve off a friend.
It was locked to O2 and had to unlock it for my virgin sim.
As soon as I had done all of that everything seemed O.K and running all fine and good. That was until I had noticed that I could not download anything directly from the blackberry app world due to a connection error.
Also I have tried downloading kik and it downloaded fine, but just as I tried to register it came up with connection error please try again. Which I thought was pretty strange due to the fact that it had downloaded perfectly fine.
Also the facebook app does the same thing, saying that I need to connect to the internet.
I have always made sure that I am connected to both wifi and mobile internet but neither seem to connect to the apps.
Normal internet functions are fine connecting to both the wifi and mobile internet so I access facebook through that.
Also blackberry messenger does not work as well.
I was wondering if anyone knew of a way to fix this?