i've seen this problem posted by other people with different macs than mine and i just wanted to see if i have the same problem or not. i got two 2GB memory modules as a gift (crucial brand 200-pin ddr2 sodimm pc2-6400 cl6) for my mid 2007 2.4ghz intel core 2 duo 20" imac (i don't know which chipset that is). the memory will not work when i put both modules in. the comp will start but wont get past the black screen. when i put EITHER of the new modules in with the old 1GB module IN EITHER SLOT, it works. so i know it's not bad memory and i know i dont have a bad memory slot (right?). as ive said, i have read that this is an issue with the memory bus speed, but i am fairly certain that the memory i received is the correct bus speed (667mhz) for the computer that i own. any help would be greatly appreciated.