Can't select the right SQL instance in a SQL 2008 R2 upgrade

Sure hope someone can help with this one. I'm running an upgrade from SQL 2005 (Version 9.4.5000) to SQL 2008 R2 Standard. When I get to the screen to select the correct instance to upgrade I can't select the right instance. There are two instances listed. One is for our Sophos software (SQL 2008 SP2 Express Version 10.2.4000.0), which I want to ignore. The other is the instance with our actual databases on it (SQL 2005 Standard Version 9.4.5000). I can only select the Sophos instance, not the one I want to actually upgrade!

Any ideas why this would not be selectable? Is version 9.4.5000 outside of the upgrade capabilities of 2008 R2? Any way around this? Help!