by using 

Process.Start(excel.exe, http://sharepoint/hr/excel.xlsx)

i was unable to open the excel file when excel prompt me for security warning and i click 'Yes'. it simply display nothing. this only happen on my machine running windows 8 but it is fine in other ppl's machine. may i know what may cause this issue? is it a security setting issue?

Hi,

In regarding of the issue, please provide us more information to assist you better.

• Do you mind telling us the whole security warning message?
• Was the security warning message pop-up when we manually opened Excel file?
• According to your description, you opened an Excel file that stored in SharePoint site. Was this security warning related to the Network?

If we can manually open Excel file (Stored with local disk or SharePoint) normally, this issue may be caused by the Process.Start function with Windows 8. If you use C#, I recommend you post the question to C# forum:

https://social.msdn.microsoft.com/Forums/vstudio/en-US/home?forum=csharpgeneral

If you have any update, please feel free let us know.

Regards,

George Zhao
TechNet Community Support