When I copy a .bin file to the mbed, 95% of the time it fails at x percent (x changes dependent on the file I want to copy/save). After this the mbed doesn't respond anymore, I'm unable to browse the mbed. My windows explorer or internet explorer just hangs. Then when I unplug the usb from my pc it responds again.

Looking in the System log of windows I find this message every time I tried flashing the mbed.

I disabled all other software including virus scanner so I'm sure no other software is interfering.

Is there anyone having an idea what's causing this problem, or how to solve this?

Try reformatting the flash drive. Make sure to unselect quick format so that it checks all sectors.

Tried that, but it hangs in the middle of the format (statusled on the mbed stops flashing)

Sounds like the flash chip got some corrupted blocks :( I think you should contact mbed support and maybe get the board exchanged.

I have the same problem with all 3 mbed boards that I have. It would find it strange if they all have corrupt blocks.

Now it think I found a sollution for the problem. It seems that the problem doesn't occure when I am using a shorter USB cable (15cm/6inch) instead of the original supplied USB cable. It also seems like the problem is bound to my machnine only. Testing on other PC's/Laptops everything is working like it should.