"White page" when use quick reply in firefox

[hiepsi@]

I have problem with quick reply in firefox, when I sumit my post white page apperence, Who has fixed this problem, please help me
Thanks
You can check this problem at: http://buonchuyen.vn/forum/register.php?do=register

The Image Verification have error with image! help me

When I logout, this page apperence: (I have upload full file include: login.php)

[Dismounted]

Please disable all modifications.

[hiepsi@]

I have fixed white page, and now I only 2 problems:

1) when I logout I get error (I think, hash md5 have problem), for every time refresh page, I get another error
2) Image verify when user register not show correct

I used windows server not UNIX

Images bellow

[Marco van Herwaarden]

I don't really understand it. You complain about white pages when posting, but link us to the register.php?

[hiepsi@]

Sorry White page has been fixed
Thanks