500 Internal Server error

[expertsiq]

could someone please assist me with this error. It is a New install works, but can not access the sub-forums. example- http://forums.parentalcontrolapps.com/forums/2-Android
I get this error:
(I know that the server is set up right b/c I have another VB4 forum working fine in on the same server, but different domain.)
-----------------------------
Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, webmaster@forums.parentalcontrolapps.com and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

Additionally, a 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request.
thanks.