Problem mit Adruino Mega 2560

Because my old arduino is gone (see other thread) i bought a new one. I connected it to my computer and tried to upload some example sketches.

After a few uploads it stopped working. As soon as the build is complete (arduino software 1.0) the computer tries to send the sketch to the arduino (RX blinks from time to time). I have to press the reset button a few times to actually make it transfer everything. then i get the "avrdude: stk500v2_ReceiveMessage(): timeout" error but the sketch is on the board :~

Any suggestions? The reset button trick doesnt work everytime so it is not a real sollution. i bought mine at amazon.

Im using Windows 7 64bit. The arduino driver is the one located in the "drivers" folder.