Hi all you guys and girls !
Very strange problem...
I don't why but with no available reason, my arduino IDE refuses to launch from this morning. I can not open anymore the arduino window...
I've decided to donwload the last arduino version : 1.6.5.
I've noticed that my security utility on my mAC OSX 10.9.5, take very long time to scan the file while installing the software.
Then I try to open it. then a pop up window comes with an alert flag and the followin words :
"No start with a file that contains "/" in its name".
I close this window and the opening of arduino terminates...
Does anyone know how I can solve this problem ? I don't understand anything about this... 
HELP !!!
Thank you for your helpfull responses !
A bunch of people have had IDE 1.6.x problems, including IDE crashes and bizarre compile errors, when they have an old 1.5.x installation. Those problems seem to be caused by out-of-date executables that the new IDE saves outside the IDE installation directory. In such cases it appears that the fix is to delete or rename the old "Arduino15" directory and re-install 1.6.x.
On Mac OS X:
/Users/username/Library/Arduino15
On Windows:
C:\Users\username\AppData\Roaming\Arduino15