Hey guys, so as of reciently I did a basic scan with Disk Utility and Onyx, and they both said i need to fix my Mac, and yet everything appeared to be ok. I tried to restart from the Mac disk by holding the C key, and NOTHING happened. It kept trying to load for 20 minutes. Obviously, something was wrong. So I tried using TechTool Pro, and booted it up from the CD. This time it worked fine, but it told me that everything was fine except for Catalog B-Tree which needed to be repaired. So here are my questions for you guys? 1. What is Catalog B-Tree? 2. How can I fix this issue? What program would fix the issue? 3. Would upgrading my computer to Lion help solve the issue? (Currently using Snow Leopard 10.6.8) 4. What would happen to my Mac if I didn't do anything to fix it?