Dunno what happen to my thread.... suddenly went missing

Anywayz can someone list out reasons of why xbox will suddenly "freeze" when just started to play games for 10minutes?

Just bought assassin creed today damn sad can't play

And I got another 2 question to ask...

1)The Network cable is attached from my xbox to my pc..... and my xbox can't login to live and sometimes will freeze when starting up

2)Where can I buy the live gold membership?

Thanks for answering....

but damn sad weh.... not even half a year already so many problems

sorry... what I meant is I plug the xbox to the modem which is connected to my pc but I can't establish a connection between my pc and my xbox....

Can't connect to live either... it pass all the test but fail the xbox live test