Hey, that's OK. I made the mistake of not reading it thoroughly.
CONFIRMED! It's the MiniDisplay plugin. When the plugin is disabled, Recorded TV records will play without problems.
It doesn't matter which settings the MiniDisplay plugin has. If it's enabled, the user will need to watch Live TV first on a MediaPortal restart before he can watch Recorded TV.
Steps to reproduce (note: you will need a preconfigured MediaPortal 1.1.0 final TV Server!)
1. Install MediaPortal 1.1.0 and the TV client final clean (no upgrade!) on a Windows 7 x64 system.
2. Start MediaPortal configuration.
3. Enable the MiniDisplay plugin.
4. Configure the MiniDisplay plugin. If you normally don't use MiniDisplay because you don't have a supported device, use "Generic Serial Character VFD/LCD driver".
5. Save and exit.
6. Start MediaPortal.
7. Try to play something from the 'Recorded TV' section. This will fail.
8. Watch Live TV for a few seconds.
9. Try to play something from the 'Recorded TV' section. This will succeed (as will any other further usage of the Recorded TV section).
Thanks, arion_p, for giving this vital clue.
I believe this is a bug. Could a moderator change the state of this thread?
Made it more clear that this bug affects Windows 7 x64 with a clean MediaPortal 1.1.0 final installation.