The dreaded 'An error has occurred' message during SPS Install

I have never had this happen to me, but last week one of my colleagues had a monkey on his back when he was trying to install SharePoint Portal Server. The install failed at the point when the Configuration database was being created with 'an error has occurred'. To troubleshoot the problem I got him to install SQL Client Utilities onto the box (which he should have anyway to ensure the SharePoint Backup/Restore works properly) and then try to create a new database on the remote server. This failed. In the end we found that for some reason, the Model database in SQL was set to Single user mode and the dba was using that connection. Once we deleted his connection and set it back to Multiuser, the install worked without a hitch.