Although many have found workarounds by using various flags, I think the ultimate solution here is getting the correct DSDT.aml for your system. I saw that a few people have mentioned a new DSDT fixing there problem but I figured I’d give a little more detail. I have been trying to install Lion on my GA-X58A-UD3R Rev2.0 since Lion was released and have been getting hung up on PCI Configuration Begin every time. Last night, before I went to bed, I would be booting Lion flawlessly. Kakewalk had always worked for me in the past when I was running Snow Leopard and a GA-EP45-UD3R board. I recently upgraded to an i7-960 and a GA-X58A-UD3R rev 2.0 board and was having absolutely NO LUCK with Kakewalk and would usually give up after a try or two seeing NONE of the flags helped me boot into the install. Here’s what I did: I prepared a bootable Lion USB flash drive using Kakewalk as mentioned in the install guide from Kakewalk. I selected the motherboard that I had and let the program do its thing. In the meantime I went onto Tonymacx86 and downloaded the CORRECT DSDT for my motherboard and bios. Having a matching BIOS and DSDT is very important for this (in my case at least). After the flash drive was finished being prepared, I copied the new DSDT from tonymacx86 onto the lion flash drive and replaced the one that was there from kakewalk. I applied the correct bios settings, made sure I had a matching bios and before I knew it, I was installing Lion. I did get an install fail while installing that was due to an error with a basesystem.pkg so I just copied the .pkg it was getting hung up on from the installESD.dmg back onto the flash drive and tried the install again. Lion was finished installing in about 10 min. Now the problem was that I couldn’t boot – I was getting hung up on the dreaded PCI configuration begin. So I booted into windows, used MacDrive to get the DSDT from the disk I installed Lion on and checked it to make sure the PCI settings were ok. They seemed to be fine, but it still wasn’t booting. So, I just replaced the DSDT on the Lion disk with the one I got from tonymacx86 and rebooted. It booted right into Lion, I set up my preferences, and it it was working great. I had sound and Ethernet, I ran system update and applied all the updates, rebooted and it booted right back up. SUCCESS There were a couple weird things with the system profiler so I just downloaded [url="http://www.insanelymac.com/forum/topic/279450-why-insanelymac-does-not-support-tonymacx86/"]#####[/url] and installed the Mac Pro profiles and that took care of it. Now, I am not saying this is the solution, but it worked for me. I didn’t have to use any flags, or change any .plist files. For those that are getting stuck, it’s worth a quick try!