500 Internal Server Error

Hello each time i tried to upload and install a new theme wordpress show me a error massage. But the different is sometime it work like 1 install on 10 theme. That is why it is difficult for me to solve the issue. Please check the massage below and if possible help me.

error massage:
============

Internal Server Error

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

Please contact the server administrator, webmaster@e3creative.net 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 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.