"4.1.8 is very reliable. No issues, even when starting and stopping multiple virtual machines a lot. Host-networking is well-thought-out. Nothing leaves the host network. I'm liking Virtualbox 4.1 more than VMWare workstation 8. The only drawback is trying to migrate machines from VMWare to Virtualbox. Can be very frustrating, but that's not Virtualbox's fault."
"Very reliable, even when making a lot of changes to the host and guest OS."