After 11 years our standing drain mysteriously overflowed flooding the house this morning. Any suggestions, similar experiences, comments will be greatly appreciated.

I assume that you mean the floor drain in the basement.
This means there is a blockage past this point.
Has the water gone down yet?
The water that backed up, where you using water in the house at the time.
If you weren't using water and it backed up it means the weeping tiles or sump pump is connected to this line. I would start with the City and ask them what procedures they have for clearing the blockage. Most jurisdictions have a 24 hour number. Failing that I would call a plumber and have the line snaked out. You can rent a snake but to get a heavy duty one it takes a bit of practice to use them so I wouldn't recommend that.
When they clear the line they will can give you better advice depending on the cause of the blockage.
One blockage in 11 years isn't cause for concern. If the plumber wants to dig right away get a second opinion.
P.S. there are lots of posts involving sewer back ups so if you review them it may give some you ideas as well.