So I have a Macbook Pro (several years old--sorry I can't remember how many exactly), that I have, in years past, upgraded with a new, larger hard drive and installed Snow Leopard on. Recently, I tried to do just a regular software update, iTunes included. When I tried to open iTunes, it said that that version could not open on the version of OS X I was using on my computer. So I went to try to upgrade to Lion, and tried to back up my computer to an external drive using Disk Utility, when it said that there were several items that needed repair, that I needed to open the computer using a different startup disk, repair the items, then back up the drive. But when I was looking up how to do that on the Apple website, they suggested starting up the computer in "Safe Mode" because I don't have another startup disk. (That entails holding down the shift key when booting the computer.) When I did that, AirPort was not working at all, so I decided to reboot the computer again. Now the computer has been stuck on the gray screen with the apple for about 30 minutes. What do I do?!