I've spent the last 2 days trying to install Windows 7 Ultimate 64-bit on my iMac (specs in my sig) and had a heck of a time doing it. I knew from experience that the 64-bit install disc would not work properly without being modified and I had the guide already from when I used to have Vista 64-bit installed. Followed the instructions to the letter and burned my new disc. Rebooted and..... a black screen with a blinking cursor? Since then I've tried 2 different guides (don't have links handy but they're the ones that always get passed around on the MR forum) and always had the same result of a black screen with bllnking cursor in the top left. Tried the original install disc (genuine retail disc) and exactly the same screen. So just to make sure I wasn't going mad I tried the 32-bit install disc which works with any mods and.... black screen with a blinking cursor. So basically my iMac is incapable of booting any Windows install disc it seems. Here's a full list of the discs I've tried to boot from... Windows 7 64 (genuine) Windows 7 64 (modified, several types) Windows 7 32 (genuine) Windows Vista 64 (genuine) Windows Vista 64 (modified) Windows Vista 32 (genuine) None of them will boot successfully. I have also tried booting using several different methods (holding option, holding C, using rEFIt boot menu) and all give the same results. I was starting to think I was going mad since I've done this procedure loads of times of my various Macs in the past and just couldn't figure out what was wrong. Then I tried one last attempt before crying for help, an external USB dvd-rom drive. So I hooked it up put in the modified Windows 7 disc and.... it boots perfectly! So I got it installed fine in the end, but would anyone have an idea why my internal superdrive no longer wants to boot Windows discs? It works perfectly fine for every other purpose so I don't think it's faulty, or at least not massively faulty. Any ideas are appreciated, thanks.