What do I need to do to run a diagnosis without blocking everything? The pizza of death is showing and the app shows up as "not responding" in the activity viewer?

I already use a thread

dim theDiagnoser as new DiagnoseThread(theDatabase, Silent)

theDiagnoser.Run



while not DiagnoseFinished or theDiagnoser.State = Thread.Running

  app.SleepCurrentThread 100

wend

NotificationManager.RemoveReceiver self

and in the thread

  if theDatabase.Diagnose(VerboseLevel, theDiagnoseFile) then

    

    'database is okay

    theDiagnoseFile.Delete

    NotificationManager.Post "DiagnoseFinished", "Success"

  'and so on

Any not responding makes users who may not be very experienced with computers force-quit my app.

Xojo 2017r1, El Capitan/High Sierra. Valentina 7.5.6.

Regards

Beatrix Willius