I am a new player of koha. I just install koha 2.2.5 on Fedora core 5. I installed everything step by step. I can access the library through intranet but can't open OPAC. When I try to access http://librarynsia.nsia.ac.nz/cgi-bin/koha/opac-main.pl , it shows message below: <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN"> <html><head> <title>500 Internal Server Error</title> </head><body> <h1>Internal Server Error</h1> <p>The server encountered an internal error or misconfiguration and was unable to complete your request.</p> <p>Please contact the server administrator, jennyzhang@nsia.ac.nz and inform them of the time the error occurred, and anything you might have done that may have caused the error.</p> <p>More information about this error may be available in the server error log.</p> <p>Additionally, a 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request.</p> <hr> <address>Apache/2.2.0 (Fedora) Server at librarynsia.nsia.ac.nz Port 80</address> </body></html> I found that some tables were not created during the installation. For example: itemtypes and systemparameters. I don't know the reason. so I want to uninstall koha and reinstall it. Can somebody tell me how to ininstall koha? Thanks