Arduino Leonardo gets disconnected during upload

I have bought an Arduino Leonardo board. When I connect it to my PC (running windows 7 and Arduino IDE v1.0.5), it shows up on Device Manager as COM7. I also select the right board and serial port on the Arduino IDE.

I try to upload an example (blink LED) to the board. But immediately after the status changes from “compiling…” to “uploading…”, the Arduino gets disconnected. My PC sounds “ding ..dong..” as if a device had been unplugged, and the Arduino Leonardo disappears from Device Manager. The port COM7 also disappears in the Serial Port list. Around 10-15 seconds later, the Arduino IDE shows the following error message :astonished::

processing.app.debug.RunnerException: Couldn’t find a Leonardo on the selected port. Check that you have the correct port selected.  If it is correct, try pressing the board's reset button after initiating the upload.
                at processing.app.debug.AvrdudeUploader.uploadViaBootloader(AvrdudeUploader.java:153)
                at processing.app.debug.AvrdudeUploader.uploadUsingPreferences(AvrdudeUploader.java:67)
                at processing.app.Sketch.upload(Sketch.java:1671)
                at processing.app.Sketch.exportApplet(Sketch.java:1627)
                at processing.app.Sketch.exportApplet(Sketch.java:1599)
                at processing.app.Editor$DefaultExportHandler.run(Editor.java:2380)
                at java.lang.Thread.run(Thread.java:619)

I try to change the USB port, unplug and plug the cable, restart my PC, and reset the board without luck. According to a thread on Internet, I press and hold the reset button after clicking on the Upload button. When the status is about to change from “compiling” to “uploading” I release the button. This time I get this error :fearful::

Found programmer: Id = "B×]"; type =
    Software Version =  . ; Hardware Version =  . 
avrdude: error: buffered memory access not supported. Maybe it isn't
a butterfly/AVR109 but a AVR910 device?

I try the same example code on an Arduino Uno (using the same PC) and it works. It just doesn't work on the Leonardo. Has someone seen the above behavior before?

(deleted)

@spycatcher2k, thank you for the useful hint. It is an official Leo, but I'm too lazy to return it back and ask for replace. So I'm gonna use my existing Uno as ISP. I found the instructions from here http://arduino.cc/en/Tutorial/ArduinoISP#.Uv5fOmJ_vwY. However, I have one more concern: The site shows 3 target types: Circuit (targeting Arduino Uno, Duemilanove, or Diecimila), Circuit (targeting Arduino NG or older) and Circuit (targeting an AVR on a breadboard). I wonder which circuit (1st or 2nd one) is for my Leo?

(deleted)

thank you very much. I followed that site and now I can upload my sketches :D