From time to time it necessitated shutting down the machine improperly. Staying on-topic though, I'm convinced the Linux kernel S3 sleep issue with the HP Envy x360 AMD Ryzen 7 4700U Processor is a suspect here for disk corruption. I will search for topics that might help me with that. So I need to take time out from this topic to study up on this and see if there is any hope for recovering usable vdi files from either of the partition backups. When I attempt to recover any of the vdi files from the partition backups, the copy process just goes on and on and on, way past the completion point I would have expected. I have Ubuntu partition backups from two dates. Late yesterday it dawned on me I've completely missed a major point of understanding regarding dynamic disks for guest VMs. Your suggestion of a hard disk corruption was daunting I've been trying to pursue it. It seems new VMs I create work fine, but old ones do not. Taking easy steps first, I tried the RAM and core count changes you suggested, cautiously in stages, but they didn't affect things so I reversed them for now. Yes the VM did work previously on this host PC.

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