BBC iPlayer Desktop
If you're having a problem playing just one programme, there could be a problem with the Digital Rights Management (DRM) licence associated with a particular download (a valid license is required to play a programme). It's possible that a licence has been corrupted during the downloading process our perhaps the licence has expired or even revoked.
DRM licence has expired.
A programme should automatically be deleted from your BBC iPlayer Download Manager once its licence has expired. If your computer wasn't connected to the internet when the licence expired, it's possible the programme may still be visible in your Download Manager. In such cases, you can manually delete the programme.
If a programme has been revoked (perhaps for legal reasons) and has not automatically been deleted you can manually delete the programme. It's also worth checking the BBC iPlayer website at a later time to see if the programme has become available again.
Corrupt DRM licence
There may be a data problem with the programme's DRM licence. If you can still download the programme, delete the one in your Download Manager and try downloading again.
More than one programme affected?
If you are having a problem downloading and playing more than one programme it's worth uninstalling and re-installing Adobe Air. For more information on how to do this please read:
Adobe Air - How do I reinstall Adobe Air?
Windows Media Player downloads
If you can only view the ten second BBC ident trailer then get a blank screen, you will need to alter your digital rights management (DRM) settings in Windows Media Player to acquire licences and rights automatically.
If you have made these changes and still have problems, you may need to see the advice on a DRM reset for Windows.
There could be a temporary problem with the network connection, in which case try again later. The BBC's servers are constantly monitored and so if there is a problem it'll be quickly found and fixed.