hmmm...as far as i can tell, the CONFIG_AEC62XX_TUNING option is no longer there in 2.4.21. the file aec62XX.c has moved (to drivers/ide/pci/) and is now at version 0.11 (compared to 0.09 in 2.4.21).
well, i reverted back to 2.4.20-ben10 and everything works fine, so it's not really an issue...
thanks anyway, -dorian