So the new 27" runs great, but instead of shutdown issues, I have wake from sleep problems. The iMac runs perfectly, then sleeps at the allotted time fine. If left for half an hour or so, it will wake normally. If left longer, it takes a couple (sometimes three) taps on the KB to wake it, when it once again runs fine. Things I've done SMC / PRAM re-et Checked Indexing I have a feeling that because I used MA to transfer my data ( Something I didn't want to do, but was persuaded, by my Apple rep to try) something has come over that should not have. I should aslo say that the fix is a re-install of ML, but I'd really like to find a better / faster fix if one exists.