An 500 Internal Error on my subdomain?

[jeffreyh]

Well, i'm here for a while, but, since yesterday, I have (caused, can be) an 500 Internal Server error. I searched the forums but nothing there. And the strange thing, it only happens on my subdomain:
http://pagetree.kalgoo.x10hosting.com/
Username: jeffreyh (obvious)

All help appreciated,
Jeffrey

 

[Chris73]

When did you create this subdomain? Is can take up to 24 hours for the php upgrade to intermediate.

 

[jeffreyh]

The subdomain has worked for about 4 months, i'm only getting the error on that subdomain, like i said:
http://pagetree.kalgoo.x10hosting.com/
My default url is: http://kalgoo.x10hosting.com/
and as you can see, default works, and sub does not.
Edit:
I've found the problem in my .htacces file on the subdomain, Some program (most likely Cpanel) had appended a rule at a same rule of another command.

So, longlive Cpanel, although it can be handy.

Thanks for the support,
Jeffrey