Page auto jump down to the midle after load

Hi,
I don't know why my site always jump down to the middle of page when finish loading. It happens to every pages, with every browsers and OS. You always have to use the scroller to scroll up to top to read or view something from beginning.
The domain is http://hoatay.net
Here is a screnn capture:

Help me plz!

Anyone could help???

Hi,

I have just checked but it doesn't happen for me, have you figured it out?

Fixed!
It caused by a pop-up module in hopepage.

It's good to know that

Have a nice day buddy,