Update Manager - Error connecting to VMware vCenter Update Manager - Database temporarily unavailable or has network problems.

I have uninstalled and reinstalled, I've triple checked that I can log on to the VCenter server using the Update Manager account that is DB Owner on the Update Manager database. I can connect to SQL using the ODBC SQL 2008 native client under that same account. But we get the same error from multiple machines when we install and run the VCenter plugin.

Any Ideas?