I have a 2007 mac pro and when I try to run OS X, I get the Apple logo then the spinning wheel during the grey screen and it just crashes (BSOD?) I tried to install a new version of OSX but I still get the crash. Tried a new hard drive, new ram, but still no go. I have a feeling its the video card, but if it was, i wouldn't even get a signal, right? What happened before was that I was able to install a new version of Snow Leopard and it worked fine, then overtime it just froze again and now it always freezes. Can't even go into boot mode to install Lion from scratch.