BIOS problems and Corrupted files


Jun 11, 2014
Ok, so i got a problem. Here it is: I have a Gateway Computer, Gateway LT31 to go in details. Recently, I saw something called Mac OS X for windows, its a program that makes your computer look like a Mac, and i'm the type of guys that loves skin packs and all. So I install it and BIG problem: After booting up, it says that authui.dll is corrupted or not designed for Windows and the screen stays black, so I cant acces my computer. I had Bitdefender installed on it, so I used the Bitdefender Rescue Mode and replaced authui.dll by another one. After that, I restart and the error doesnt show up !! No, its another one ! I instantly knew that my system32 folder may be entirely corrupted so I abandoned. I then lended the computer to my dad, and I dont know how but when I came up, It ask me an HDD User Password !!!! He doesnt know it, so how am I doing. I did some research, but nothing. Im currently trying to make a bootbable USB to install Windows 7 starter, but will I be avaible to Boot USB instead of the BIOS ? The password instantly shows up after the manufacturer screen, so I cant do nothing. Help please !!! ( I'm currently on Vista on the laptop)