Arduino Serial Communication PLEASE HELP

I'm trying to use arduino as an input to Flightgear, but when i start flightgear it doen't respond until I disconnect the arduino. I've also noticed that arduino keeps sending data even with no programs opened, i also checked and this doesn't happen on other computers, so i deduced that there's some kind of conflict, PLEASE HELP.

Well what type of arduino, what type of serial communication, what software on your arduino etc…

Can’t help without info

arduino uno rev3, latest arduino ide, and i don't know what do you mean for what type of commincation, but it's the normal Serial communication, that one with Serial.begin(9600). Sorry for bad english

What happens when you try to run the sample program that displays an ASCII table. You can find that program from within the IDE using this menu sequence:

File --> Examples --> Communications --> ASCIITable

Run the serial monitor (Ctrl-Shift-M) and make sure the baud rates match. Then tell us what you see.

ASCII Table ~ Character Map
!, dec: 33, hex: 21, oct: 41, bin: 100001
", dec: 34, hex: 22, oct: 42, bin: 100010
#, dec: 35, hex: 23, oct: 43, bin: 100011
$, dec: 36, hex: 24, oct: 44, bin: 100100
%, dec: 37, hex: 25, oct: 45, bin: 100101
&, dec: 38, hex: 26, oct: 46, bin: 100110
', dec: 39, hex: 27, oct: 47, bin: 100111
(, dec: 40, hex: 28, oct: 50, bin: 101000
), dec: 41, hex: 29, oct: 51, bin: 101001
*, dec: 42, hex: 2A, oct: 52, bin: 101010
+, dec: 43, hex: 2B, oct: 53, bin: 101011
, dec: 44, hex: 2C, oct: 54, bin: 101100
-, dec: 45, hex: 2D, oct: 55, bin: 101101
., dec: 46, hex: 2E, oct: 56, bin: 101110
/, dec: 47, hex: 2F, oct: 57, bin: 101111
0, dec: 48, hex: 30, oct: 60, bin: 110000
1, dec: 49, hex: 31, oct: 61, bin: 110001
2, dec: 50, hex: 32, oct: 62, bin: 110010
3, dec: 51, hex: 33, oct: 63, bin: 110011
4, dec: 52, hex: 34, oct: 64, bin: 110100
5, dec: 53, hex: 35, oct: 65, bin: 110101
6, dec: 54, hex: 36, oct: 66, bin: 110110
7, dec: 55, hex: 37, oct: 67, bin: 110111
8, dec: 56, hex: 38, oct: 70, bin: 111000
9, dec: 57, hex: 39, oct: 71, bin: 111001
:, dec: 58, hex: 3A, oct: 72, bin: 111010
;, dec: 59, hex: 3B, oct: 73, bin: 111011
<, dec: 60, hex: 3C, oct: 74, bin: 111100
=, dec: 61, hex: 3D, oct: 75, bin: 111101
>, dec: 62, hex: 3E, oct: 76, bin: 111110
?, dec: 63, hex: 3F, oct: 77, bin: 111111
@, dec: 64, hex: 40, oct: 100, bin: 1000000
A, dec: 65, hex: 41, oct: 101, bin: 1000001
B, dec: 66, hex: 42, oct: 102, bin: 1000010
C, dec: 67, hex: 43, oct: 103, bin: 1000011
D, dec: 68, hex: 44, oct: 104, bin: 1000100
E, dec: 69, hex: 45, oct: 105, bin: 1000101
F, dec: 70, hex: 46, oct: 106, bin: 1000110
G, dec: 71, hex: 47, oct: 107, bin: 1000111
H, dec: 72, hex: 48, oct: 110, bin: 1001000
I, dec: 73, hex: 49, oct: 111, bin: 1001001
J, dec: 74, hex: 4A, oct: 112, bin: 1001010
K, dec: 75, hex: 4B, oct: 113, bin: 1001011
L, dec: 76, hex: 4C, oct: 114, bin: 1001100
M, dec: 77, hex: 4D, oct: 115, bin: 1001101
N, dec: 78, hex: 4E, oct: 116, bin: 1001110
O, dec: 79, hex: 4F, oct: 117, bin: 1001111
P, dec: 80, hex: 50, oct: 120, bin: 1010000
Q, dec: 81, hex: 51, oct: 121, bin: 1010001
R, dec: 82, hex: 52, oct: 122, bin: 1010010
S, dec: 83, hex: 53, oct: 123, bin: 1010011
T, dec: 84, hex: 54, oct: 124, bin: 1010100
U, dec: 85, hex: 55, oct: 125, bin: 1010101
V, dec: 86, hex: 56, oct: 126, bin: 1010110
W, dec: 87, hex: 57, oct: 127, bin: 1010111
X, dec: 88, hex: 58, oct: 130, bin: 1011000
Y, dec: 89, hex: 59, oct: 131, bin: 1011001
Z, dec: 90, hex: 5A, oct: 132, bin: 1011010
[, dec: 91, hex: 5B, oct: 133, bin: 1011011
, dec: 92, hex: 5C, oct: 134, bin: 1011100
], dec: 93, hex: 5D, oct: 135, bin: 1011101
^, dec: 94, hex: 5E, oct: 136, bin: 1011110
_, dec: 95, hex: 5F, oct: 137, bin: 1011111
`, dec: 96, hex: 60, oct: 140, bin: 1100000
a, dec: 97, hex: 61, oct: 141, bin: 1100001
b, dec: 98, hex: 62, oct: 142, bin: 1100010
c, dec: 99, hex: 63, oct: 143, bin: 1100011
d, dec: 100, hex: 64, oct: 144, bin: 1100100
e, dec: 101, hex: 65, oct: 145, bin: 1100101
f, dec: 102, hex: 66, oct: 146, bin: 1100110
g, dec: 103, hex: 67, oct: 147, bin: 1100111
h, dec: 104, hex: 68, oct: 150, bin: 1101000
i, dec: 105, hex: 69, oct: 151, bin: 1101001
j, dec: 106, hex: 6A, oct: 152, bin: 1101010
k, dec: 107, hex: 6B, oct: 153, bin: 1101011
l, dec: 108, hex: 6C, oct: 154, bin: 1101100
m, dec: 109, hex: 6D, oct: 155, bin: 1101101
n, dec: 110, hex: 6E, oct: 156, bin: 1101110
o, dec: 111, hex: 6F, oct: 157, bin: 1101111
p, dec: 112, hex: 70, oct: 160, bin: 1110000
q, dec: 113, hex: 71, oct: 161, bin: 1110001
r, dec: 114, hex: 72, oct: 162, bin: 1110010
s, dec: 115, hex: 73, oct: 163, bin: 1110011
t, dec: 116, hex: 74, oct: 164, bin: 1110100
u, dec: 117, hex: 75, oct: 165, bin: 1110101
v, dec: 118, hex: 76, oct: 166, bin: 1110110
w, dec: 119, hex: 77, oct: 167, bin: 1110111
x, dec: 120, hex: 78, oct: 170, bin: 1111000
y, dec: 121, hex: 79, oct: 171, bin: 1111001
z, dec: 122, hex: 7A, oct: 172, bin: 1111010
{, dec: 123, hex: 7B, oct: 173, bin: 1111011
|, dec: 124, hex: 7C, oct: 174, bin: 1111100
}, dec: 125, hex: 7D, oct: 175, bin: 1111101
~, dec: 126, hex: 7E, oct: 176, bin: 1111110

I think that’s something normal

Ok - so how do you connect your arduino to Flightgear? And what do you expect to happen?

I suppose you have read this http://wiki.flightgear.org/Howto:Use_Arduino_with_FlightGear

Make sure you don't have the arduino IDE serial console opened at the same time you run the software

yes i read that article, and i expect flightgear to start beacuse the loading freeze to "finalizing position", then when i disconnect arduino, flightgear finishes the loading and starts. I also tried to reconnect arduino when flightgear has been already started but nothing happens

What do you have running in the arduino ?