Excel VBA from an Internet Explorer Browser

I am needing to develop an application that will be a document on our company intranet. On the opening worksheet, the user will select desired criteria, then click a "Run Report" button. The VBA code will then open a .csv file and produce criteria-based reports. I've done extensive Excel VBA coding in my career, but have no experience with running it from within a browser, which is how it appears when you open the workbook from the intranet link. Code that works from Excel does not work from the browser. The first line of code I tried was "Workbooks.Open filepathname", and it gets Run-time error 1004: Method 'Open' of object 'Workbooks' failed. Is there a different set of code needed when running Excel VBA from a browser? What other problems and differences am I going to run into? Any guidance would be appreciated.

I have a partial solution, but it needs some tweaking. To get it to run from Excel instead of from the browser, do the following:
1. Open My Computer or a Windows Explorer window.
2. Select File Types
3. Type or Select XLS (or whichever extension the workbook has that you will be opening).
4. Click Advanced.
5. Uncheck "Browse in Same Window" and click OK.

It will then open the document as a spreadsheet. However, this has to be done on each PC that will be using the document. That's fine for my situation, but I can't come up with a way, from the VBA code, to determine which way they have opened it. If they open from the browser, it still gets the run-time error when they run the report. If I could at least detect and produce a clean error message, I'd be happy, but I've found no property or way of determining the situation. Application.Name or Application.Parent both contain "Microsoft Excel", and it ignores the On Error statement I put in front of the Open. Any ideas?