Hi! I posted this over on the Apple support forums but haven't gotten much help. It's kind of a strange problem but maybe someone has come across something similar? Thanks for any help or ideas! ---------------------- Hopefully someone can help me with this because I'm completely at the end of my wits! I recently decided to clean up my mac by upgrading my OS X Tiger partition to Lion and my Windows Vista partition to Windows 7. Initially, I didn't realize I needed to upgrade from Tiger to Snow Leopard before I could install Lion, so I put in my Lion DVD and booted into the install menu, but when I tried to install it over the top of Tiger it gave me an error. I didn't realize what was wrong (now I realize you can't intall Lion on top of Tiger but the error message doesn't say anything about that). So, what I did is, still in the Lion Boot menu, I went into the Disk Utility and decided to erase my mac partition and try a clean install. That didn't work either, and so then I decided to just go back to Tiger -- but this is where I ran into my problem. Then I think I did something stupid. I decided to upgrade my Windows partition first, but instead of installing my new version of windows over my old Bootcamp partition, I instead installed it to the partition that used to be my TIger partition. So, essentially I now had two bootcamp partitions. My thought was that I could then just copy over my essential files from my old windows partition to my new one before wiping it and re-installing OS X to my old Windows partition. I think this was a mistake because now I've found that I can't get my mac to boot using an OS X install DVD -- neither my original Tiger discs nor the Lion disc that I used to erase my partition in the first place. I'm also no longer able to see my bootable partitions by holding down the "option" key when booting. I also can't put my Macbook into Target Disk Mode either. If I try any of these things all it does is hang on the boot until I reset it by hitting the power button. All of this was working fine before I went through the above process. There is nothing wrong with my hard disk because I currently have two Windows partitions and they are working perfectly. It's almost like I've accidently deleted some bios-level operational data that usually allows you to boot to an install DVD or boot to Target Disk Mode. I've had macs for a long time and never had this problem before -- unless it was a hard disk or memory issue, but, as I said before, I don't think that can be the case because my windows partitions are working perfectly. I apologize for the long-winded description but I always figure it's better to be as detailed as possible if you expect someone else to help you solve a problem. My advanced thanks for any help you can give! I'll be checking this hourly, so let me know if there is any other information that would help! --eric P.S. Just a couple of misc info that might help: 1. Without being able to go into my "About this Mac" menu I can't remember exactly what model my Macbook Pro is, but I believe it's 2nd or 3rd generation Macbook Pro. I think I bought it in 2008...? I believe it's a Core 2 Duo. 2. Windows is telling me that I have 3 Gigs of RAM (although I thought I had four...) 3. Finally, my internal superdrive died years ago, so I'm using a USB DVD drive to boot OS X from. I've used this external drive to install OS X before though, so I don't think it is the problem. Thanks again!