A. This is because tempdb gets created with model's attributes at SQL startup. To overcome this :-
1. Start SQL Server with the -T3607 trace flag. See the books online for how to do this.
2. Login to SQL Server as sa with ISQL or ISQLW.
3. Do a DUMP TRANSACTION model WITH NO_LOG
4. Stop SQL Server
5. Remove the trace-flag
You should now be able to restart SQL again.