I had that problem (or something very similar, vid corruption and lockup) on an AMD64 machine with both the 32 and 64 bit versions of Ubuntu. I didn't get to troubleshoot it properly (husbands new machine for work, he was just letting me experiment for the day), but my hunch was something flakey with the bios. Either that or flakey hardware likely either video or ram but I lean more to a weird bios setting. Wish I knew more. Good luck

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