I installed Mountain Lion on my iMac and the wifi connection only lasts for 15/20 minutes. I then have to restart, except that after the new installation, my machine will not restart. I have to Shut down and start again. My macBook Air does not seem to be effected by this. Pretty poor show after all the hype. You would expect it to be right before they release it. This also effects the Time Capsule back up which is wireless.