BD 2017 causing problems on Windows 10 x64 with Office

BitDefender 2017 free antivirus is interfering with Office 2010, causing problems opening .xls files in protected view (excel xls files downloaded via mail with Outlook) with Excel 2010. It won't happen with Excel 2016. Disabling the antivirus won't help, but uninstalling it makes the problem disappear. When BDefender 2017 is installed and running, Excel will try to open the file, will show "opening in protected view..." but will never open. The problem is easily reproducible. System Windows 10 x64 up to date. 

NOTE: remember that Office 2010 open these "suspicious" files under a protected view using sandbox. 

PS: Also, couldn't report this via mail because doesn't work. "ERR_TOO_MANY_REDIRECTS".