Arduino Mega2560 can't be programmed via USB

Take a look at this issue: Google Code Archive - Long-term storage for Google Code Project Hosting.

Edit your boards.txt file and change
From:
mega2560.upload.protocol=stk500v2

To:
mega2560.upload.protocol=wiring

@ Louis Davis

Thanks very much for this solution, my Arduino 2560 (early version) on XP Home Edition just stopped uploading and hanging. Com port was still in the tools menu, and serial monitor was still working but no uploading.

thanks again, been driving me nuts for ages