When launching SQL Server Management Studio after installing SQL Prompt, the following error message may appear:

To resolve this problem:

1. Open a command prompt and change directory to the SQL Prompt installation folder.
2. Run the following:
   For version 3.x : %SYSTEMROOT%\Microsoft.net\Framework\v2.0.50727\regasm "%ProgramFiles%\Red Gate\SQL Prompt 3\RedGate.SQLPrompt.SSMSUI.dll" 
   For version 4.x: %SYSTEMROOT%\Microsoft.net\Framework\v2.0.50727\regasm "%ProgramFiles%\Red Gate\SQL Prompt 4\RedGate.SQLPrompt.SSMSUI.dll" 
   For version 5.x: %SYSTEMROOT%\Microsoft.net\Framework\v2.0.50727\regasm "%ProgramFiles%\Red Gate\SQL Prompt 5\RedGate.SQLPrompt.SSMSUI.dll"
   This will register SQL Prompt as a Management Studio add-in. 
3. If the command is successful, run SqlWb.exe /setup (SQL Server Management Studio 2005) SSMS.exe /setup (SQL Server Management Studio 2008, 2008 R2 and 2012) to re-initialize SQL Server Management Studio's interface.

If the problem persists, it may be necessary to reinstall SQL Prompt:

1. Open Add/Remove Programs or Programs and Features from the Windows Control Panel.
2. Select SQL Prompt then click Repair.