Hello, My computer: 13" Mid-2012 MBP, 4GB ram, 500GB Harddrive, 2.5 ghz I5. I was caught in a boot loop the other day - white screen with apple that wouldn't load beyond 75% on the bar - and had to do a system restore. Apple forced me into a High Sierra upgrade from El Capitan. High Sierra has made my computer run terribly. Worst of all, it's my work machine and I can barely even use my internet browser now. I need to quickly restore to an older OS. My computer came with Mountain Lion, which I can't revert to through original system restore (Ctrl-opt-shift-power, I believe) since I have the newer OS on it currently. I don't have any discs. I'm leaving on Monday for 3 weeks abroad and need my computer for work. It's practically useless with High Sierra. Can I go into Disc Utility and wipe my hard drive clean, then do a system restore to Mountain Lion by using that keystroke? I've got everything backed up but don't want to wipe it clean if it's just going to force me back into High Sierra. Help please!