500 Internal server error came back

[tester02mail84]

Still this error:
"Internal Server Error

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

Please contact the server administrator, no-reply@x10hosting.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 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request."

This time it always happen to me and its damage seriously to my site whenever i operate at Admincp or taking a longtime action.
I set all folders to 755 and files to 644 but it doesnt work, and when that error happen, it usually duplicate my action. Please help me! I dont know what to do. So bored.

 

[Zubair]

I am getting mysql error not Internal Server error

General Error
SQL ERROR [ mysqli ]

Table 'quake123_forum.phpbb_config' doesn't exist [1146]

An sql error occurred while fetching this page. Please contact an administrator if this problem persists.

 

[tester02mail84]

yes, as i said before, it duplidate any action when appear and that is a error when i'm installing (uninstall) phpBB mod "met" 500 error, i can fix it and then 500 error happen again although i refresh browser or back to the previous page.

 

[tester02mail84]

Well, no reply anymore. When you guys fixed that error please sticky answer thread. I will Inactivity in some days. Thanks.