A document with the name 'SOLVER.XLA' is already open

Summary

The message, "A document with the name 'SOLVER.XLA' is already open.  You cannot open two documents with the same name, even if the documents are in different folders.  To open the second document, either close the document that's currently open, or rename one of the documents."  might appear upon opening of Excel 2003 while Risk Solver Platform is installed.  It is triggered when Excel attempts to open both the standard Excel Solver's Solver.xla and Risk Solver Platform's Solver.xla.  (This was done in the earliest version of Premium Solver Platform so users could run their macros immediately without having to perform any additional steps.)  This article gives the reason why this message is appearing and two different methods for resolving the error.

Solution

The solution to this problem is to prevent Excel from attempting to open both files (standard Solver's Solver.xla or Risk Solver Platform's Solver.xla) at the same time either by disabling the Standard Solver or by not allowing the Risk Solver Platform's Solver.xla to open.  The user can decide which file not to open to meet his/her specific needs. 

Each time Excel is opened, an OPEN statement inside the Registry notifies Excel to open the standard Excel Solver's Solver.xla and places Solver on the Tools menu.  If this OPEN statement is removed, this Solver.xla will not be opened and the error will not be displayed.  To remove this OPEN statement, simply remove Solver from the Excel Addins menu by clicking Tools  > Addins and uncheck Solver.  Solver will be removed from the Tools menu. Now close and reopen Excel to confirm that the error message is not displayed.  To use the standard Solver, you must add the Solver back to the Tools menu by clicking Tools > Addins and check the Solver Addin. Note:  You will need to remember to uncheck Solver in the Addin list before Excel is closed.  Otherwise, you will receive the message above upon re-opening of Excel.   

If checking/unchecking Solver each time Excel is opened/closed seems tedious, please read on for a possible alternative option.  

In Risk Solver Platform, Solver.xla is only necessary (and it only is used) for controlling Solver through VBA from an Excel macro using the Legacy API Solver functions, such as SolverSolve, SolverOK, etc.  If no such macro exists, then the option Load Vx.0 VBA Macros (Tools > Premium Solver > Model > Options tab) can be unchecked, where "Vx.0" refers to the version of Risk Solver Platform currently in use. If this option is unchecked, Risk Solver Platform will not open its own Solver.xla file and the error will not be displayed.  Warning:  If Load Vx.0 VBA Macros is unchecked, you will not be able to run Risk Solver Platform through VBA using the Legacy API functions such as SolverSolve, SolverOK, etc.  However, you will be able to call the Solver through VBA by using the new Object-Oriented API functions, which can do everything that the Legacy API functions can do, and much more.

In later versions of Excel, the standard Excel Solver's file has been renamed to Solver.xlam.  As a result, this message will never appear in Excel 2007 or Excel 2010.