I need help from people who are knowledgable abou these Mac wonders of the world and single user mode. I'm trying for the life of me to run "memtest" in single user mode and am finding it impossible. After I boot into single user mode, I get a "Shell>" prompt. I type in /sbin/fsck/ -y to do some check thing. I then type in /sbin/mount -uw / Both times I get an error saying that "/sbin/yada yada yada is not recognized as an internal or external command, batch or whatever" No commands work at all. I have no clue what I'm doing and am using instructions from where I got the memtest app. Sure I could just run it from the Terminal but then you're not testing all of the RAM, only the available portion. There's a huge chunck that won't be tested as OSX is using it. I want to do this as I just upgraded RAM to 8G with Crucial and now my MBP is acting very slow and weird. HELP???? Why does this have to be sooooo hard.