You'll get the error "500 - internal server error" due to some invalid setting in your application. With out having more detailed information error we can not say what causes the error to occur.
To View a detailed error message add the below settings in you'r web.config.
<system.web>
<customErrors mode="Off"></customErrors>
</system.web>
<system.webServer>
<httpErrors errorMode="Detailed" />
<modules runAllManagedModulesForAllRequests="true"/>
</system.webServer>
</system.webServer>