I've been putting up with this for a little while now. I'm running mainly Apple Apps such as Aperture, Pages, mail, Safari, iTunes with a bit of CS5 thrown in. iMac, 27, 3.4 i7, 12Gb Ram. At least 3-5 times a week I'm having major system crashes needing a reboot. In between I'm suffering extremely laggy performance just for simple tasks such as scrolling. Apps freeze, apps shut down without notice. Why? The iMac 24" 2.93, 8Gb Ram I had before ran Aperture (for Example) really well with no problems AT ALL. In fact I rarely had a catastrophic system crash with SL - maybe two? What gives? The only thing that's different (Apart from a major iMac upgrade, and moving from 8 to 12GB ram) is the operating system. I know, I know. You're using the same apps as me and everything's going just fine for you. That's great, but I want to hear from the users who've had similar issues, and maybe even fixed them. Are you there?