Random crashes, need help troubleshooting

[zithro]

BTW, just read that post : QSB-079: Two IOMMU-related Xen issues (XSA-399, XSA-400)

Subsequent DMA or interrupts from the device may have unpredictable behaviour,
ranging from IOMMU faults to memory corruption

Have you updated already ? It may be as simple as that ^^