Arduino UNO resets when connected to MAC OS 10.10.5

Hi everyone,

so I bought some arduino stuff to play with over the weekend. Did a few projects but have trouble with my arduino crashing(resetting).

If I run the blink program on pin 13 it it blinks for 4 seconds and then the blinking gets fast - then nothing - and then restart.

If I use a USD transformator to only provide power this does not happen.

If i include a serial connection to my mac it does not happen. I noticed this when I started adding sensors to my build. Then when i attached the LCD to output reading and took away the serial output it started to crash again.

So i think that my uno gets a reset signal from the mac IF it is not busy sending data over serial. I tried to search with google and on the forum but I might use the wrong input since I get no results for this error ... sorry ... new to this.

Any suggestions?

Kind regards from Sweden!