To completely remove SONAR from your computer and reinstall it, follow the steps below.

Please note that this will remove any effects presets and key bindings you may have made in SONAR. You can back these up separately if you like, using Utilities menu > Cakewalk Plug-in Manager, Edit > Preferences > Customization – Keyboard Shortcuts and Edit > Preferences > Customization – Colors. Type F1 in these views for detailed instructions or read this Cakewalk blog post on how to do this. Note that this blog post focuses on migrating to a new computer, scroll down the post to find the backup instructions.

1. Uninstall SONAR.
   This is normally done within the Cakewalk Command Center. Open the Command Center, right-click on “SONAR <Platinum/Professional/Artist>” and select Uninstall. This will not remove any of your plug-ins, project files or audio data.      
   • If you downloaded SONAR directly from your Cakewalk account, you can uninstall SONAR from the Windows Control Panel > Programs and Features.
   • STEAM users can right-click on SONAR in their Software Library and select “Delete Local Content.”
      
2. After the uninstallation completes, open the Run Prompt.
   In Windows 8, 7 and Vista, open the Run Prompt by holding down the “Windows” key and pressing “R” on the keyboard.
    
3. At the Prompt, type regedit and click [OK].
    
4. Click [Yes] if asked to allow the program to make changes to your computer.
   Important: When you access the Registry Editor, create a backup by going to File > Export. In the Export Registry File window that comes up, make sure “Export range” is set to “All” and that “Save as type” is set to “Registration Files (*.reg)”. It is very important to create a backup of your registry because if you accidentally delete a registry key there is no undo function. You can, however, double-click on the Registry backup you made above to re-import your registry keys if you make any mistakes. You must re-import your backup (if needed) before restarting your computer.
    
5. Delete the following Registry keys: If you do not have one of the Registry keys below, simply proceed to the next one on the list.
   HKEY_CURRENT_USER\Software\Cakewalk Music Software\SONAR\<Platinum/Professional/Artist>
   HKEY_LOCAL_MACHINE\Software\Cakewalk Music Software\SONAR\<Platinum/Professional/Artist>
   HKEY_LOCAL_MACHINE\Software\Wow6432Node\Cakewalk Music Software\SONAR\<Platinum/Professional/Artist>
    
6. Open the Run Prompt again.
    
7. Copy and paste %appdata%\Cakewalk into the prompt and click [OK].
   On Windows 8 and 7, the “AppData\Roaming\Cakewalk” folder will open.
    
8. Right-click on the SONAR <Platinum/Professional/Artist> folder and choose “Delete.”
    
9. Delete the contents of the following directory: C:\Program Files\Cakewalk\SONAR <Platinum/Professional/Artist>.
   • If you have installed a 32-bit version of SONAR on a 64-bit operating system, the default location will be C:\Program Files (x86)\Cakewalk\SONAR <Platinum/Professional/Artist>.  
   • STEAM users should open the following directory and delete its contents: C:\Program Files (x86)\Steam\SteamApps\Common\Cakewalk\x64\SONAR.
     Note: this path changes to C:\Program Files\Steam\steamapps\common\Cakewalk\SONAR if you are on a 32-bit only system. If you have installed STEAM to a custom location you'll need to adjust accordingly. 
      
10. At this point you can reinstall SONAR from the Cakewalk Command Center, by downloading the installers from your Cakewalk Account or STEAM

This should eliminate any software irregularities that are causing your problem.