When I try to change my nameservers to ns1.x10hosting.com and ns2.x10hosting.com, I get errors spit back at me. I use 1and1, but I don't think that the problem is on their end.
have you tried asking they help desk, if they have one, since 1and1 is not controlled by x10, so it is most likely that is 1and1, since my domain registar is working with the DNS