Hey guys, i've creeped the forum and saw this is an open issue with no one solution but heres my take on whats happened up till now:
In december '10 I got the 2560 mega and was able to get it to work perfectly with 0020 OR 0021 (don't remember which) but it was functioning well with W7.
Yesterday, I tried to upload a sketch with OSx10.6.8 with 0022 and I kept on getting the avrdude: stk500_2_ReceiveMessage(): timeout error and the program did not stop the upload.
It would keep on displaying this message may times until it would eventually upload a single sketch randomly (no sequence of plugging in/out and restarting the arduino program gave consistent upload success). Sometimes i'd notice LED 13 (pin 13) would flash as usual before upload, TX and RX begin flashing for a quick moment, then die off before a full load sequence. Then either all LEDs are off, or LED13 would blink at odd intervals.
The same unsuccessful results follow with windows 7 attempt.
On the other hand, the 0022 version uploaded sketches without problem to the duemillanova chip.
Any idea as to why this problem is persistent? (i will try later to downgrade to version 0020 and 0021 and see if there is any success).
Thanks!