Mega 2560 Firmware (XP)

I have great problems with my new Mega2560 and Ubuntu.
It seems that this is neccessary:

After that: "sudo dfu-programmer at90usb82 erase" an error in Linux occurs.
It was not possible to execute that: "sudo dfu-programmer at90usb82 flash Arduino-usbserial-mega.hex".

I think i have damaged the firmware.
Now i want to switch to Windows XP.
The board is detected as a mega2560 DFU, but no driver from the "arduino-0022/drivers"-folder will be accepted.
The green LED is on and the yellow one blinks.
Flip told me that "AtLibUsbDfu.dll" is not found.
But it is in the "C:\Programme\Atmel\Flip 3.4.3\bin" and the "system32" folder.
Maybe it is not registered correctly?
resrv32 doesn't work (dll not found).
How can i flash the firmware? There is only an explanation for the Uno.
I have tested it with different Win and different cables for days and days. It is allways the same.
Who can help?

did you read through this?
Do you have any other Arduinos laying around?