This is a quick post as I'm just about to go out, I'm sorry if it's a little vague! For the last 2 hours I've been trying to upgrade the RAM in my 1.25GHz Powerbook, from the original 512mb's to 1024mb's. I purchased the RAM from Crucial, buying 2 x 512 sticks. Loading the RAM into my computer I've now noticed that the lower of the two memory slots is no longer responding (according to the computers System Profiler) to either the new RAM, or the original sticks. I've tried many variations but nothing has worked so far... Has anybody else come across this same problem? If so, how did you fix it? I'm considering taking the computer to my local Apple Approved store (The Apple Centre Warrington), but cannot be without the computer - it is my only computer and is what I do all of my work on. If it has to be sent away, can I expect to receive a replacement? Also, if you were in my position, would you take the computer back with the original RAM loaded in the slots? Although in my opinion highly unlikely, is there any chance that a hardware problem such as this could be as a result of me loading Panther (approx a week ago)? Any advice would be great! Andy.