Alright I have a biggggg problem with my mac, and would appreciate any advice. Firstly, the facts about my issue: I do not have an OS lion installation disc I do not have a backup (if need be I can backup my mums Macbook pro and use that if that is possible?) I have a Macbook Pro. I downloaded Windows by using the disc, not through bootcamp as it would only allow me to use a Windows 7 disc. Alright, heres the problem: Earlier today I installed Windows XP 2002 onto my Macbook Pro, I believe I must of downloaded it over the OS partition, a I can now only use Windows and that automatically boots up when I restart my computer. Holding down Option doesnt work, as the only one there is Windows. I also tried to do Command+R and re-install Lion, however on the last page it says something about my startup disc, it says: Select the disk where you want to install Mac OS X The only option is called untitled however this says: "This disk doesnt use the GUID Partition Table Scheme. and basically says I can't do it. I also do not have a disc as I bought it off someone and it came without it. It does have the option to back-up my mac. What can I do to resolve this? Thanks for your help Also would using my mothers backup work?