[jlegate]

I am sorry I didn't mention before. I didn't have this problem after I turned the mod off. but i don't know whether it's a one page checkout problem, because it's a random problem, sometimes it happens twice a month, sometimes it doesn't happen. I have contacted Bill and X-Cart Support regarding this problem when I used version 4.1.5, both of them suggested me to upgrade, but the problem still exists after the upgrading.