I recently had the exact same problem with Win98SE on VirtualBox on an AMD CPU. There the solution was to run
vBoxManage.exe modifyvm "Win98" --cpu-profile "Intel Core i5-3570"
vBoxManage.exe modifyvm "Win98" --cpu-profile "Intel Core i5-3570" I think there is a similar option in Hyper-V to change used CPU profile.