id summary reporter owner description type status component version resolution keywords cc guest host 12064 Suddenly no VM's will start - all give a RPC_S_SERVER_UNAVAILABLE error at 0% Bryan Bentz "I was in the process of creating a new machine, and it wouldn't start (more in a bit) - I then tried to start up a few old, reliable machines, and got the same behavior. The only change was that on startup a new version was mentioned; I installed it and saw this behavior. After some web research I went back to version 4.2.12, and still see the same problem - but this may have to do with having installed the 4.2.16 version and then, perhaps, and incomplete removal. I suppose technically this applies to both versions, as the problem shows up in both. When I try to start any machine, I see a small popup, ""Starting virtual machine..."" and ""0%"" - that never changes. My host OS is Windows 7 Ultimate; I have to kill the process for that machine manually. When I do, I get a popup from Virtualbox; the detailed error message is: Result Code: RPC_S_SERVER_UNAVAILABLE 0x800706BA (0x800706BA) Component: ProgressProxy Interface: IProgress {c20238e4-3221-4d3f-8891-81ce92d9f913} Web searching shows this, or something like it, was a problem years ago, but apparently fixed. I found current ticket #10747 that looks similar. The VM I was trying to start as the main test case is a Windows 98 machine, fairly vanilla. I certainly haven't changed any of its attributes (e.g., hardware acceleration options) since it last ran. I have 17 VM's, all of some level of importance; it would not be a minor effort to recreate them, even if that helped. I tried to create a new Windows 2000 machine from scratch and had the same problem, that is the exact same hang and detailed error message. I'm willing to invest some time to help fix it, if any testing I can do on this end might help." defect new other VirtualBox 4.2.16 "RPC_S_SERVER_UNAVAILABLE 0% ""won't start""" all Windows