This message indicates that the conditions specified by the model to solve is not in a valid form when passed to the underlying Solver32.dll for processing. This can occur if the wrong version of either Solver.xla or Solver32.dll is installed or if (more likely) if the values of certain hidden defined names used by the Solver have been modified either manually or via VBA programming. To avoid this type of error, make sure that there are no defined names beginning with "solver" in the spreadsheet.
