Hi all, I have tried searching everywhere for more info on this but I just can't work out what's going wrong. I am trying to install an Agility 3 to a 2011 MBP 13" running Lion, which I hate. 1st attempt: Remove HDD and replace with SSD. Result: Turn on machine holding down Option/Alt key and insert Snow Leopard CD. Select SL CD when prompted. CD starts to boot only to get the 3 beeps and no further activity, indicating memory error. Memory hasn't been touched. Replaced original HDD and all was fine again. 2nd attempt: Fit SSD in to Optibay with original HDD in original bay in machine. Result: Machine boots fine from original HDD. SSD is detected in OSX, initialized and partitioned. I am able to transfer files onto and off of the SSD. Attempted to install OSX Snow Leopard (The OS I wish to run) to the SSD with original CD in external Optical bay but Lion tells me I can't run a Snow Leopard install within Lion environment. 3rd Attempt: Fit SSD back in to HDD bay and original HDD in to Optibay. Turn on machine with Option/Alt held down again hoping that the partitioned drive will be recognised. Am able to select the Mac OSX CD in an external CDROM but not far in to loading of eh CD, again I am faced with the 3 beeps. I cannot get this thing to work for love nor money. Any other threads I find with this problem are inconclusive. Surely I'm no the only one who's had this problem and wanted to find a solution. Have I missed something really simple here? I am running out of ideas, and patience, as I have seen positive reports of others doing this in the past. Thanks in advance, Rob.