[Hawk552]

This isn't very well coded... try something like this:

//Server Shutdown by Remo Williams

#include <amxmodx>
#include <amxmisc>

new countdown = 10

public plugin_init() 
{
    register_plugin("Server Shutdown", "1.0", "Remo Williams")
    register_concmd("amx_shutdown","servershutdown",ADMIN_IMMUNITY," - shuts down server in 10 seconds")
}

public servershutdown(id) 
{
    if (!(get_user_flags(id)&ADMIN_LEVEL_A)) 
    { 
        console_print(id,"[AMXX] You have no access to this command") 
        return PLUGIN_HANDLED 
    } 

    client_print(0,print_chat,"***** Warning! Server Restart Imminent! *****")
    set_task(1.0,"countdownact",_,_,_,"b")

    return PLUGIN_HANDLED
}

public countdownact()
{
    countdown--
    client_print(0,print_chat,"%s seconds until server restart.",countdown)
    if(countdown <= 0)
    {
        client_cmd(0,"retry",1.5)
        server_cmd("quit")
    }
    return PLUGIN_HANDLED
}