Thanks for the help ... (Big Edit because I think I found the problem... didn't realize there was already a reply)

Here's a follow-up for anyone else with a similar problem

I logged onto a 3rd server, thinking I could now change the SQL services account to the new account (I'm local admin on the box). It accepts the change, but I get an error of "Access Denied" after chaning the account, and SQL Services won't start. Event Log says: Server local connection provider failed to listen on [ \\.\pipe\SQLLocal\MSSQLSERVER ]. Error: 0x5

Worse than before !

I search the error and found this, suggesting a reboot should fix it http://blogs.msdn.com/b/sql_protocols/archive/2006/03/09/546655.aspx

" ... snip ... If the listening named-pipes are not closed properly during the last shutdown of SQL Server, there will be orphan named-pipe handles in the windows kernel file system. Since the listening pipes are opened ACLing to the current user, if you happen to switch SQL Server to run under different account, you will get error 0x05(ERROR_ACCESS_DENIED). ... snip ...

The solution is to either switch back to previous account and make a clean shutdown of SQL Server, or reboot the machine. In most cases, I feel the later is faster.... snip"

... so far, so good: