Hi, I'd just like to add that I am having this same problem. I tried unparking my domain (hjproductions.org) and setting as my default with the new userpanel. I've had the domain parked to my account hjproduc.x10hosting.com for several months now and working fine. However, after doing this my site keeps going up and down giving me a "Page Not Found" error.
I've been changing back and forth (several times getting an error telling that my domain was assigned to another user) trying to get it to work but now even when I set it back to my old account domain and park hjproductions.org to hjproduc.x10hosting.com, it gives me and several other people the error.
Also, the X10Hosting Services Up/Down thread is showing me that all the services are down. I'm thinking there's something wrong with X10Hosting's name servor because I've had my domain pointed towards the correct x10hosting name servors for several months and it has worked perfectly fine until now.
I made a topic about this several days ago and it has been completely ignored.
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http://forums.x10hosting.com/showthread.php?t=17260
Subdomain: hjproduc.x10hosting.com
Domain (Purchased): hjproductions.org
Username: hjproduc
I really appreciate this hosting because its the best I've ever found, but now I'm getting real fruststrated because I've been dealing with this problem for several days now and have been completely ignored when asking for support.