delay until problem in Windows

Simplified code:

task body Some_task is

    Time_For_Next_Frame : time;

    procedure Fetch_Frame is
      -- Here is where Time_For_Next_Frame is calculated
    begin
         Send_Frame;
         Time_For_Next_Frame := Clock + Desired_Delta_T;
    end Fetch_Frame;

begin

   loop

      select
          ...
      or
         delay until Time_For_Next_Frame;

         Fetch_Frame;

   end loop;

end Some_Task;

Symptoms:

After over 24+ hour operations it seems that delay gives no delay no
matter what value there is on Windows system .  On Linux all is fine.

If I replace delay statement with

delay Desired_Delta_T;

all seemed fine.  Does anyone knows of that limitation?

George.