I have a mid-2010 27" i5 iMac (my 3rd iMac in as many years) maxed out with 16GB of Crucial memory. I'm aware that iMacs have potential issues with 16GB configurations -- there's tons of noise about it all over the net. Seems a workaround is simply to not run 16GB configurations. I'm a huge abuser of VMware and would rather not knock the mem config down if I can avoid it. According to some posts online, iMacs are very picky about their memory modules and the particular brand of chips used on the modules but my research is thus far inconclusive about what brands work and what don't. So I'm reaching out here to anyone who may have experienced this "random shutdown syndrome" and managed to solve it without sacrificing memory count. What brand memory has been working for you (16GB configuration only) in your late iMac? Also, after these random shutdowns occur (and it's totally random; could happen once in a couple months or a few times an hour) the kernel.log advertises the "Previous Shutdown Cause" as -128. Does anyone know what this code means? One post I came across implied that it means the SMC simply doesn't know why the machine shut down (not very useful!) Thanks. PS -- The only common ground I can find between the random shutdowns the machine has had is that I'd been working in Safari just prior to the shutdown. I'd literally click on a link then *poof*, black screen. Reproducible? Unfortunately not. Not at will anyway (which is a characteristic of memory problems).