Microsoft has released updates that have caused some downloaded files not to open, most notably HTML with .xls extension. The updates in question are:

• Windows Update KB3115262 (Excel 2013)
• Windows Update KB3115130 (Excel 2010)

There are several options that can eliminate the problem:

Option 1

• Control Panel > Internet Options
• Security Tab > Trusted Sites
• Add the site you are downloading from to the trusted site list

** You will need to re-download excel files once this change is made. Files previously downloaded when untrusted may still open blank **

Option 2

• Go into the properties of the file you have saved to your computer (right click it, then left click properties)
• Click Unblock
• Click Apply
• Open the file

Option 3

• Open Excel Go to File Options
• Click Trust Center -> Trust Center Settings
• Go to Protected View. there are 3 options that show that were all clicked. Uncheck the first option that reads -- "Enable Protected View for files originating from the Internet"

Option 4

• Open Excel Go to File Options
• Click Trust Center -> Trust Center Settings
• Go to File Block Settings
• Uncheck Web Pages and Excel 2003 XML Spreadsheets

Option 5

• Uninstall the previously mentioned update that applies to your Office version