changing main domain

[phoenixracing]

why do i get this message
A system error occurred while processing this action.

Error Code: F3F45C7A
as the result when ever i try to change my main domain from phoenicracing.x10hosting.com to phoenixrcracing.co.uk my own domain i purchased

 

[phoenixracing]

i have already posted a thread about this but with no luck from the ideas people gave me came on today to find it had been closed but still need to change this i dont want this domain parked i want it as my main domain

 

[phoenixracing]

anyone able to help is there a problem with this as it looks like others have the problem to