Different sporadic SQL Server errors
(More like a Delphi problem to me)

In my case, it had to do with a recent reinstallation of Access.
Access MDAC not beeing compatible with sqlncli11.dll, this mean I had to rebuild the whole application.

If I get it right, Delphi compiled only the units that I modified, using (I don't even know why, as I don't use Access) the current MDAC and it collided with the old DCU that were compiled using the old MDAC.