If the pi is running and i unplug the wifi dongle and then put it again the raspberry restarts. Does anyone else has the same problem or knows a solution?
Unfortunately it's a problem with the latest revision of pi's, not your wifi dongle. It would happen with any USB. There is a missing capacitor (AFAIK), compared to other revisions. This means that the power supplied to the pi becomes unstable for a second when the USB is plugged in. This fluctuation in power causes the Pi to restart. This is a known bug, and a new revision will surely fix this.
To get around this, plug in a powered USB hub. As you wont be hot plugging a USB straight into the Pi itself, there will be no restarts. However, if you do plan on plugging a USB into the Pi. Please turn it off; this random restart can cause the OS to become corrupt.