I thought I had successfully managed to install 4.0 from DVD until booting from the hard drive.
Knoppix/Debian had seen my IDE controllers and drives as UDMA, and tried unsuccessfully to turn on the DMA for them. The result was a lockup with the error message being 'Drives Busy', then an error status code. Even putting ide=nodma in the kernel line did not stop the OS from trying to make the DMA part active later on. The drives/controller had run under Win98 with DMA active and no problem, but I have read that people have been having problems with Kernel 2.6 (which Knoppix 4.0 uses) and DMA. I had to stop the DMA from being running initially and also from being activated later on during the hotplug session. Now I have a working machine, although I cannot share my drives with my windows machines, but thats another matter.
Try running your PC using the DVD as normal (DMA is switched off by default) then enable it from the main menu. My machine locked up when I did this, which proved running the drives with DMA enabled on my PC with Kernel 2.6 was a no no. Perhaps you can disable it in your bios settings just to test. I hope I've given you another avenue to investigate.