A corner path failure can be caused because may be you are using zone value in Position and after that timer.
e.g.
MoveL pPick, v1000,z50,tool0;
Waittime 0.5;
I am also observed this type of issue in my program, then I rewrite this program
e.g.
MoveL pPick, v1000,fine,tool0;
Waittime 0.5;
And after that Corner path failure this event message is not coming again on screen.