I was casually on the Internet as usual, running 10.6.8, Firefox 45.9, on YouTube, and all of a sudden, the video freezes, the last played back bit of audio keeps looping, the cursor won't move, and the computer won't respond at all to keyboard commands. Wouldn't even enter sleep mode with a press of the power button, so I had to do a hard reboot. When it came back up, it showed the "Your system shut down because of a problem" message, I click "show details", and it gives me this. Fri Oct 6 00:28:13 2017 panic(cpu 4 caller 0x9d4c97): NVRM[0/2:0:0]: Read Error 0x00000100: CFG 0xffffffff 0xffffffff 0xffffffff, BAR0 0x92000000 0x90436000 0x092880a2, D0, P1/2 Backtrace (CPU 4), Frame : Return Address (4 potential args on stack) Kernel Extensions in backtrace (with dependencies): com.apple.GeForce(6.3.6)@0xc5c000->0xd12fff dependency: com.apple.NVDAResman(6.3.6)@0x96e000 dependency: com.apple.iokit.IONDRVSupport(2.2.1)@0x961000 dependency: com.apple.iokit.IOPCIFamily(2.6.5)@0x928000 dependency: com.apple.iokit.IOGraphicsFamily(2.2.1)@0x93f000 com.apple.nvidia.nv50hal(6.3.6)@0x15d5000->0x19e9fff dependency: com.apple.NVDAResman(6.3.6)@0x96e000 com.apple.NVDAResman(6.3.6)@0x96e000->0xc5bfff dependency: com.apple.iokit.IOPCIFamily(2.6.5)@0x928000 dependency: com.apple.iokit.IONDRVSupport(2.2.1)@0x961000 dependency: com.apple.iokit.IOGraphicsFamily(2.2.1)@0x93f000 After that, I fire up Console, and the entry closest to the freeze period was this one. "10/6/17 12:28:44 AM com.apple.WindowServer Fri Oct 6 00:28:44 Mac-Pro.local WindowServer <Error>: kCGErrorFailure: Set a breakpoint @ CGErrorBreakpoint() to catch errors as they are logged." If it is of any help, I also just recently installed an IDE hard drive into the second bay in the optical drive bays. I also set that IDE drive to be the Time Machine disk, and Disk Utility doesn't display any errors for it. This came as a great shock after all the wonderful stories and reviews I've seen/heard of this machine's robustness and reliability, and I really hope there's nothing wrong with any hardware, aside from maybe the hard drives. Any help would be massively appreciated.