Hyper-V user here. It's fine - I run 12-15 VMs (4 of which are Linux) at a time (full production environment with virtual networking) on a 4 year old Dell T3500 Quad Xeon with 32Gb of RAM. Sounds like your hardware is broken/crap.
When you have Hyper-V installed, you have to be exceptionally careful about what drivers you have installed. I've even seen a Bluetooth driver bluescreen the management OS when Hyper-V was enabled.
This is just the nature of hypervisors. Most drivers are only tested on an OS that's running directly against the hardware. Run them through a hypervisor, and their behavior becomes unpredictable.
Ultimately, Hyper-V is a hypervisor, and it competes against ESX -- not VMWare Workstation. That's why it's best run on workstation-class or server-class hardware. Basically, situations where the hardware vendor might actually keep the drivers up-to-date. On consumer-level hardware, it's a crapshoot.
More than one hypervisor per machine is not a good idea. You'll get the same problem with Intel HAXM and VMware as well.
To be fair the problem with this is that the whole Intel virtualization architecture is hacked on the side (as is every other damn feature since the 80186).
