Hurricane can not take off!!!

[frogpowder]

As the thread title, I'm having trouble with my Hurricane MkI. A few days ago, I still operated it normally. But now things've changed. Now I can not take off with flap at 0 degree (although I could do that a few days ago). So I made it 20 degree, then the aircraft tended to nose down. If I resisted it, the aircraft would be very unstable and very hard to take off. I seems to have not enough force to lift.
Please help me!