DLLHOST.EXE Shutdown Not Working!

I have an IIS app running in high isolation, although the dllhost.exe COM+
process isn't shutting down & accumulated memory released. I've tried to set
the 'Server Process Shutdown' on the server package in COM+ in an attempt to
shut-down the process when idle for more than 3 mins (the default), but this
ain't happening.

I've read that this may be because IIS is caching the TypeLibs so I tried
setting the AspEnabletypelibCache flag to try stop IIS doing this, if indeed
it was, but the process still doesn't shut down.

Is there another way to get the process to shutdown (I thinkin this must be
happening because references to various dll's aren't being released in the
code), I would hope there to be a way to tell IIS/COM+ to shut-down the
process anyway. I don't want to have to run a script to keep unloading the
process.