ATMEGA in a Car !! HELP!!

Hi everyone ,
i use ATMEGA 328P in a car

the details ==>>
i use :16MHz Crystal ,
power the circuit with 7805 with 0.33 and 0.1uf connected to Car battery,
VCC connected with 0.1uf and AVCC too, AREF connected with 0.1uf to GND
i use Analogue and Digital pins,
the board contain LCD,7Segments,Bar graph, Shift registers.

The problem ::
the ciruit works well, but if i switched the light or started the engine , ATMEGA going carzy (the lcd give me uknown characters , 7 Segment ,and bar graph too).

I Think::
because the car is a noisy enviroment (Alternator,lights ,horn,etc..).

HELP::
How can i cancel the noise.
How can i use ATMEGA in noisy enviroment (Cars).

Show us an image of your wiring.
Please show us a schematic of your circuit.

.

i attached it

One of the best ways to filter out alternator noise is a DC-DC "buck" convertor...
or similar

12-14 Volts go in and 5V (adjustable) comes out. Buy one power-rated to match your needs. IF you wish to use the onboard regulator, too, just adjust the output to around 8.9V-9V and utilize the barrel jack. Or save power and adjust for exactly 5V and use the 5Volt pin input bypassing the onboard regulator.

Ray