Parallels 12 has brought my machine to a screeching halt. I don't like it, I don't want it! I want to go back to v10.(whatever I have). Can I reinstall 10 over 12, or do I have to remove 12 first? If I remove 12, how much Winblows will I lose? I have a LOT of 3d printer files on Win10. Mac 3d printer files haven't been upgraded since before Nov 2013, Windows are upgraded a near monthly. If I have Win running in the background and use the Mac to go online, it takes 1 min - 1 min 15 seconds to log onto my home page - Yahoo. Without Win running it logs on in 5 - 10 seconds. Wasn't like this in V10. I have a late 2013 IMac with 16 G memory. (Worst 2000 I ever spent.) Not a happy camper here... Thanx for any help Ski