How To Make MS Excel 2010 Open Documents In a New Instance

This is a registry tweak to make MS Excel 2010 open documents in new instances when they are opened by double clicking on filename in Windows Explorer (or similar programs).

Step 1 - Backup registry

Step 2 - Make sure the backup can be restored

Step 3 - Changes to the registry

There are three values that need to be changed to make Excel documents in a new instance each time for XLSX extension.

- In the registry editor, Navigate to the following path - HKEY_CLASSES_ROOT -> Excel.Sheet.12 -> shell -> Open -> command

- Double click on the (Default) entry

- Now, paste the following at the very end of the value: "%1"

  Be sure to add space after /dde. The value should look something like this: "path" /dde "%1"

- Now, rename the "command" registry entry right below the (Default) entry to "command2"

  Check the screenshot below

- Rename the folder "ddeexec" to "ddeexec2"

  Check the screenshot below

This should allow excel to open files in new instances by default. also disabling DDE in the Excel options does not always work. This fix is for XLSX extension.

For XLS files, make similar changes to Excel.Sheet.8

For XLSM (with macros) files, make similar changes to Excel.SheetMacroEnabled.12

For CSV files, make similar changes to Excel.CSV

NOTE - In order to avoid registry tweaks, excel can be manually opened in a new instance each time, and then the spreadsheet can be opened in that instance. However, that option does not seem to work in Windows 8.1. I went ahead and made registry tweaks in Windows 8.1 and it works fine.