When OpenInBrowser in the Save method is set to true, the Excel spreadsheet or Word document does not open in the Internet Explorer Browser window as expected. Instead, the spreadsheet opens in Excel or the document opens in Word.
Using a browser other than Internet Explorer
The plugin that is used to display Office files in the browser is only available in Internet Explorer, so other browsers cannot display Excel or Word files within the browser. However, you can set whether you want to always open the files in Excel or Word, or save them to disk by default.
When a user is sent an Excel or Word file, a dialog box prompting to Open or Save the file pops up. The user can choose an option and then check the “Do this automatically for files like this from now on” box to have it remember this choice.
Chrome defaults to saving the file to disk. If you want to open a file type automatically in Excel or Word, download a file of that type. Once the file is downloaded, right-click the file in the download bar at the bottom of the browser. Select “Always open files of this type”.
Using Internet Explorer
It is likely that the “Browse in Same Window” is disabled for the file types (XLS, XLSX, XLSM, DOC, DOCX, DOCM).
Previously, this option was available under Folder Options > File Types > Select a file type > Check Browse in the same Window.
Starting in Windows Vista, this option is no longer exposed and the registry needs to be modified to enable certain file types to open in the browser. This Microsoft Knowledge Base article explains how to enable the behavior by modifying the registry: A new window opens when you try to view a 2007 Microsoft Office program document in Windows Internet Explorer 7 or Internet Explorer 8.