Andrew,
I've tried doing the update through HP SIM itself. So i click the SW icon on the server, then select update to baseline as the VCRM only has the last SPP loaded in it.
Then on the next screen i try a run now, i've tried select install if VCA not present, or fail if the install if VCA is not present, but all updates seem to fail.
So are you saying you manually open HP SUM and then push the updates through that. If so do you use HP SUM on the VCRM server? Which in my case is also the HP SIM server.