Update: it works but I need a prior login.
If the error message is shown, I logon via "sign in" above and then call my bookmark again.
Weeks before, such a workaround was not necessary ...
Edit:
If that does not help (because it is said "sign out"), I reduce my link to
http://social.microsoft.com/Forums/en-US/. There will be another login link on the upper right corner, called "log in to forums" or similar.
After logging in there I call my bookmark once or even twice; then it works.