By default it should stop and restart IIS unless you are running a version of IIS which doesn't support it. As far as I can remember its supported on IIS5.0 & above e.g. Windows XP, Windows 2000 & Windows 2003.
50mb isn't a huge amount unless the webserver only has marginally more memory than that and the memory is required for other things.
Thinking about it, you may need to just uninstall and reinstall IIS .. backup your metabase first and you should be able to do it without too much hassle.
I suspect it's one or more object's have become un-registered somehow or perhaps even a corrupt metabase (worst case)
The only consistent dll associated with this error that a search found for me was comsvcs COM+ Services