Why does Live Mesh require UAC?

At this point it’s worth talking about UAC and why the Live Mesh client requires that UAC be turned on. If you’ve tried to install Live Mesh on a system with UAC disabled you’ll have found that the installer blocks on this configuration. There’s a technical reason why we impose this restriction: In Vista RTM with UAC off, COM does not read the per-user hive, meaning COM objects registered per-user do not work. Since Live Mesh installs per-user without elevation it is subject to this restriction. To prevent users from installing on unsupported configurations we added a block in our installer when UAC is off. Fortunately there’s light at the end of the tunnel for users that run with UAC disabled. Windows Vista SP1 has a change that allows per-user COM when UAC is disabled. With the release of SP1, we have begun validating that Live Mesh fully functions with UAC disabled, but haven’t yet finished our testing. Expect this configuration to be supported in a subsequent refresh. As you can probably guess, this also means that even after you install, UAC must remain enabled for Live Mesh to work correctly. If you turn UAC off, we won’t be able to find any of our COM objects.