the best solution;
Advanced Fix - This can be addressed by manually editing the registry. If you are not comfortable with editing the registry or have not done it before, be sure to back up your registry first by clicking File | Export and setting the "Export Range" to "All"
- Open the run prompt by clicking START | RUN
- Type the following into the prompt: regedit
- Click [OK], this will open the Registry Editor
- Navigate to the following registry key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Drivers32
- Clicking on the Drivers32 key will display a list of entries in the right pane
- Locate the entries with the name midi, midi1, midi2, midi3 etc..
- In the 'Data' field the name of the driver will be listed
- Duplicates and unused entries can be deleted by right-clicking on the entry and choosing 'Delete'
- Once all duplicates (or all midi entries) have been cleared out close the Registry Editor and then re-install your device drivers
more info here