Originally posted this in the Mac Mini forum, but having traced the issue to a peripheral, I thought I'd post again here. I have a EyeTV Hybrid USB TV Tuner and a 2012 Mac Mini. They worked fine at first, but recently this issue developed: When I try to boot with the tuner connected, the Mini hangs at the first white screen. This is before the Mini will respond to the keyboard to I can't safe boot or anything. I have verbose boot on, but again the white screen comes before anything appears. As soon as I unplug the device, everything is back to normal and the machine boots. Swapping out other devices makes no difference. When the machine is booted and I plug in again, sometime the tuner works fine, sometimes it isn't recognised at all (nothing in system profiler). In the latter case it often springs into life at random 2-10 minutes later. Now for the weird thing. If the tuner has been working and I restart the machine, no problem. If I shut it down for ten minutes then boot, no problem. If I leave it off for several hours and then boot, back to the white screen. Similarly, if I restart before the device has started working, white screen. This leads me to suspect that the device is not initialising properly. I read somewhere that USB devices have to exchange some messages with the computer before they will be recognised as USB 2.0/3.0 rather than 1.1. If this step fails the device does not receive enough power. Is this correct, could this be my problem. I also read some weird stuff about people putting EyeTv/WinTV devices in the oven to cure a similar problem, but this seems a bit crazy. Although saying that the issue did start during a period of very cold weather... Should add that I've tried a reinstall of EyeTV, SMC reset, NVRAM reset... some of these seemed to help temporarily but the issue always came back.