Impact of using ForceShellExecute=1 in Office 2007, 2010 and 2013

For different reasons (such as this), your company may find that it has a need of changing the way that Office opens links, and force Office to use the Windows way of opening links. To achieve this, you will use this registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\9.0\Common\Internet
and a Reg_Dword called ForceShellExecute with value 1
(N.B. this key refers to 9.0 for all versions of Office)

This will make Office use Windows way of linking instead of Office way of linking. So it will basically be the same as if the user opened the link by Start – Run – Paste the link – Enter. The below article summarizes and discusses the known behavior changes and problems you may see when setting this key, so that you can make a meaningful decision about if you should use it or not.

Difference 1: Files opened from Office will open in separate instances
With ForceShellExecute=1 set, the links you click will open in separate Office instances in the Task Manager. And when you are working with 2 Office files in separate instances, some limitations apply. Here is an example of such a limitation: You cannot paste any attributes into a workbook in another instance of Excel.
Another issue could be that some add-ins may not be constructed for the scenario that 2 Excel/Word/PPT files are running in separate instances. You will need to check with the developers of the add-ins that you use if they will be impacted by this.

Difference 2: A linked workbook does not open when you click a hyperlink in an Excel 2010 workbook
This is documented in http://support.microsoft.com/kb/2597992. If you make sure you install updates from Microsoft Update, you will not need to take any action on this one.

Difference 3: A second presentation does not start until the original presentation is finished in PowerPoint
This is documented in http://support.microsoft.com/kb/916776. As seen there, you will need to set another (low impact) registry key to solve this one.

Difference 4: A warning message will come up when opening files from within Office
You may find that you get the following warning after setting this key:
Some files can contain viruses or otherwise be harmful to your computer. It is important to be certain that this file is from a trustworthy source. Would you like to open this file?
You can disable this by following this article.
(You may however want to make the changes in“HKEY_LOCAL_MACHINE\Software\Classes” instead of“HKEY_CLASSES_ROOT”in order to avoid this.)

Difference 5: Links to Excel open without going to the right sheet, and links to Word open without going to the right bookmark
After setting this key, you may find that Excel links open without switching to the requested sheet, and that Word files open without scrolling to the requested bookmark. The reason is that Windows linking, which this key enforces, does not support linking to bookmarks. This can be considered the major tradeoff of using this registry key.

Security impact of using this key:
Unless there is a security problem in your environment with opening files from Start – Run, using this key should not have any security impact.

Supportability impact of using this key:
ForceShellExecute=1 is documented in a KB and is therefore considered a supported registry key, and as clearly can be seen in the links above, there have been an amount of fixes released in the past to ensure that it keeps working.

Summary:
Hopefully the above gave you an overview of the impact that usage of this key will have on your organization, from a technical, compatibility, security and supportability point of view. As seen above, not using the key will save you from some trouble, but most of this trouble already has a solution if you run an updated version of Office. Difference 5 will be your main tradeoff, and Difference 1 will be the one whose impact will vary greatly depending on your environment.