modelsim error when simulating an asynchronous fsm

asynchronous_fsm : process 
(
	reset ,
	address ,
	data ,
	general_register_1 ,
	general_register_2 ,
	event_register ,
	mask_register ,
	events ,
	dsp_on ,
	state ,
	any_event_detected ,
	unmasked_event_detected
) is
begin

	if reset = '0' then 
		
		dsp_on <= '0' ; 
		general_register <= ( others => '0' ) ;	 	 	
		mask_register <= ( others => '0' ) ;	
		event_register <= ( others => '0' ) ;		
		fsm_state <= fsm_idle_state_0 ;
		
	else

		case state is
		
			when idle_state =>
						
				if any_event_detected = '1' then
					event_register <= events ;
					if unmasked_event_detected = '1' then
						state <= on_state ;	
						dsp_on <= '1' ;
					end if ;	
				end if ;		
				
			
			
			when on_state =>
			
				if general_register_1 ( 0 ) = '0' then 						
					dsp_on <= '0' ;	
					state <= idle_state ;	
				end if ;						
				if address = mask_register then 
					mask_register <= data ;						
				elsif address = general_register_1_address then
					general_register_1 <= data ;
				elsif address = general_register_2_address then
					general_register_2 <= data ;					
				end if ;						
				
		end case ;
		
	end if ;
	
end process asynchronous_fsm ;