Before you mark this as a duplicate for this What should I do when Ubuntu freezes? note that it is for issues after login, not before. I have tried previous versions of the kernel, Alt-F2, Ctrl-Alt-F1, Alt-SysReq REISUB, Ctrl-Alt-Backspace, none work once it stops. Last thing on screen is "Stopping save kernel messages" if I hide the splash screen. Tried everything in recovery mode.
For some reason I cannot boot from CD either, so am kinda stuck. I had added a line to fstab that was not accepted, but earlier in the week it did boot from CD and I was able to remove the offending line, so it does not look like a grub issue. It seems maybe it is related to the AMD Catalyst drivers I loaded, but those have worked for 2 weeks at least, so no idea really. Is there a list of what runs when during the boot sequence so I know what the next task after the "Stopping save kernel messages"? Would be a clue at least.