Opening Excel File using Task Scheduler

It might be the DCOM permissions issue. One solution is to set Excel to run as a specific user through DCOM permissions.

1. Open Component Services: Start > Run > DComcnfg
2. Drill down to: Component Services > Computers > My Computer > DCOM Config
3. Right-click on 'Microsoft Excel Application' and choose Properties
4. In the 'Identity Tab', select 'This User' and enter the username and password of an interactive user account (domain or local) and then click Ok

Keeping it as the interactive user or the launching doesn't work with the task scheduler, even when setting the task to run under an account that has admin rights to the machine.