Genellay this is not a good thing to do! But sometimes when you work in development environments you need to do this to keep the Certificate Error warning from coming up. In my case it was needed because the logout is actually a logout on several levels using HTTP-redirects to travell between them. This was made impossible by the Certificate Error warning page.
To turn the warning off, change the followin registry key to 0.
Don’t forget to turn it back to 1 after testing though! Otherwise you are a bit unprotected.