Hi Mits2020 and thank you for taking the time to write your reply. I've been away on vacation and here is what I've done.
Hardware:
Dell Precision Tower 3420
Processor: Intel(R) Core(TM) i7-6700 CPU @ 3.40GHz
Physical Cores: 4
Memory: 31.9 GB
Display Adapter: Intel(R) HD Graphics 530 AMD FirePro W2100 (FireGL V)
BIOS Name: BIOS Date: 06/14/19 02:44:12 Ver: 2.13.1
BIOS Version: 2.13.1
BIOS Release Date: 2019-06-13
Motherboard: Dell Inc. 08K0X7
1. First is the hardware. Since everything seemed to work OK for 3 years (and then for 2 months on WIn10), you may have a hardware degradation issue. Are you sure that the hard disk(s) where the host and guests are installed has good health (no bad sectors) and that the filesystem is intact (chkdsk)? Have you ever tested your RAM for defects with Memtest? How much RAM do you use and how much do you allocate to the guest(s)? Is the RAM you use on your motherboard's Qualified Vendor List?
Response: I ran Dell full hardware diagnostics on all components, including exhaustive tests. It ran for hours. I also ran chkdsk, and checked the event logs for any obvious hardware, disk or file system errors and didn't see anything obvious.
2. Since you have a vanilla Dell workstation I am assuming there is no exotic hardware in your PC like e.g the latest generation of Intel or AMD CPUs, weird network cards, scsi controllers etc, correct?
Response: Correct, this is a standard Dell build, no custom hardware or components.
3. Is your motherboard's BIOS updated to the latest version? Are you using any kind of overclocking?
Response: Bios and all hardware drivers are completely updated, and no overclocking or any custom fans or anything. See Bios info above
4. Finally, do you have a decent power supply (or has it perhaps aged) that can handle all your hardware properly?
Response: This is the same basic 350 Watt power supply that shipped with the system. I have no reason to believe it's faulty, since these problems basically began after I upgraded the Host OS to Windows 10 Professional.
5. Then is the software. Since everything seemed stable with Windows 7, then Windows 10 may be the issue,. Please provide details on how you are creating the Windows 10 virtual machines. Are you using original iso files from MS (checked with checksums), or are you using a CD or USB?
Response: For the Host I ran an in place upgrade using the Microsoft Windows Media Creation Tool. I've used this tool a bazillion times with no problems and the Host OS seems completely stable.
6. What build/flavor is this Windows? Have you tried using the latest ISO from Microsoft?
Response: The Host and VMs are running Windows 10 Professional. Remember that I upgraded the VMs from Windows 7 to Windows 10 first, and then let them run for weeks before performing the upgrade on the Host. So the in place upgrade on the VMs was successful and the VMs were stable for weeks after the Windows 10 upgrade. However, after we upgraded the host and stared having problems with the VMs, I actually created an entirely new Windows 10 Professional VM from scratch and it's crashing as well. I don't believe it's the upgrade or installation media.
7. Are you using any exotic software on the host that requires intensive 3D graphics?
Response: No exotic software that is graphic intensive on the Host or the VMs.
8. Have you tried disabling 3D acceleration on the guests?
Response: Are you talking about in the VM configuration, disabling 3D Acceleration? No I have not disabled 3D Acceleration, I'll try this tonight.
9. Finally, are you using default options for the CPU virtualization? In Virtual Machine Settings - Processors the three checkboxes for the Virtualisation Engine should be unchecked. Also how many cores has your CPU host and how many do you use in the VMs? Have you tried reducing the number of cores for the VMs (e.g 2 instead of 4) to allow possibly better scheduling for the host?
Response: This is how the VM guests are configured.
8GB RAM
Number of Processors: 1 (This was set to 2, I changed it to 1 but still crashing)
Number of Cores per processor: 2
Total Processor Cores: 2
Virtualization Intel VT-x/EPT or AMD-V/RVI is deselected
Virtualize CPU Performance counters is deselected
Additional Information: I also disabled VSS on the system drive so the VSS service is no longer writing recovery points for the drive the guests are on.
i appreciate the help
