oric_dan(333):
Aha, that didn't seem to come out so clearly previously, with all the comments from others.
50 boards and no problems sounds like a lot of others with shaky board designs, starting over
on avrfreaks.
Ok.
And what about those messages in the AvrFreaks forum and in other sites coming from users that are not able to use a bootloader to flash a sketch on that chip?
Those messages are old (3/4 years old), the problem is known. Several people had this issue.
The user that suggested the use of the RC filter on the AvrFreak forum isn't a newbie. I gave him credit and I solved the problem.
BTW, a friend of mine had tried 5 different chips with sevaral datacodes and he wasn't able to bootload a sketch. He tried to use an FTDI card and an MCP2200 as USB/serial converter but he didn't solve.
PS:
I tried my chips on a breadboard. The SAME circuit on the SAME b.b. worked perfectly with an Atmega644PA.
I flashed the bootloader and was able to upload a sketch on it using its bootloader. So I can exclude a circuit problem (in my case).