If you need to support multiple customers running different operating systems, consider using virtual machines (VMs). You can have as many different configurations as you like and run multiple sessions at the same time running different operating systems. If one VM crashes, you can reboot it without restarting the computer or affecting the other VMs. If you make a configuration change that crashes a VM, just revert back to the previous configuration.
I don't know what business you're in, but if you are developing or supporting software, virtualization is the only way to go. VMware is the leader in this technology, you can download a free version of their hypervisor. Or you can use the Microsoft hypervisor, "Hyper-V". There's also a Linux-based hypervisor called Xen.