Parallels Toolbox for Windows crashes when using Clean Drive tool

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Every time I start Windows on PC or Windows as a virtual machine, I get System.NullReferenceException notification from Parallels Toolbox.


  1. Click on Start menu and type Clean Drive, then click on the Clean Drive app.

  2. Click on the cogwheel button and make sure that option Remind to clean drive is enabled.

  3. Close Clean Drive tool.
  4. Click on Start menu and type regedit then click on the suggested item Registry Editor.

    If prompted by User Account Control (depends on Windows settings) click Yes.
  5. In the appeared window locate the following key:

  6. Double-click on the CleanDriveShowNotifDate item and input the following value in hexadecimal:

  7. Then click OK button and restart Toolbox.

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