Will do but at the moment I have a 1284p happily flashing away whilst running at 20MHz. I will give it some further testing later.
/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/bin/avrdude -C/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/etc/avrdude.conf -v -v -v -v -patmega1284p -cstk500v1 -P/dev/tty.usbserial-A40081RP -b57600 -D -Uflash:w:/var/folders/Iy/IyymAOAIFPKmxm-fGSEuf++++TI/-Tmp-/build3529885193917945027.tmp/Blink_1284P.cpp.hex:i avrdude: Version 5.11, compiled on Sep 2 2011 at 18:52:52 Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/ Copyright (c) 2007-2009 Joerg Wunsch System wide configuration file is "/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/etc/avrdude.conf" User configuration file is "/Users/maniacbug/.avrduderc" User configuration file does not exist or is not a regular file, skipping Using Port : /dev/tty.usbserial-A40081RP Using Programmer : stk500v1 Overriding Baud Rate : 57600<snip>avrdude: verifying ...avrdude: 1188 bytes of flash verifiedavrdude: Send: Q   avrdude: Recv: .  avrdude: Recv: .  avrdude done. Thank you.[code]You did just recently re-flash the bootloader, and you were certain to flash the 16MHz bootloader and not the 8MHz one?