Resetting the BIOS/CMOS (by selecting "Load Optimized Defaults") appears to have fixed this issue. 5 hours so far with no hitches (freezes). I can't imagine why any BIOS setting would cause this issue with Ubuntu but I'm optimistic about the problem being fixed.
IIRC this box is 16 months old. The only BIOS options I clearly remember tweaking were the boot order and some enable-virtualization setting. I'll continue testing for a few days and see if I can isolate a single setting that causes the issue.
Resetting the BIOS/CMOS (by selecting "Load Optimized Defaults") appears to have fixed this issue. 5 hours so far with no hitches (freezes). I can't imagine why any BIOS setting would cause this issue with Ubuntu but I'm optimistic about the problem being fixed.
IIRC this box is 16 months old. The only BIOS options I clearly remember tweaking were the boot order and some enable- virtualization setting. I'll continue testing for a few days and see if I can isolate a single setting that causes the issue.