Maybe this is the issue your are seeing:
http://code.google.com/p/arduino/issues/detail?id=806
The suggested fix is to edit boards.txt and change the following line:
mega2560.upload.protocol=wiring
Maybe this is the issue your are seeing:
http://code.google.com/p/arduino/issues/detail?id=806
The suggested fix is to edit boards.txt and change the following line:
mega2560.upload.protocol=wiring