|If you have removed all your Add-ins then it is probably your Normal.dotm file|
that is corrupt.
The full extent of the /a switch is:
"Starts Word and prevents add-ins and global templates (including the Normal template) from being loaded automatically."
Since you have no Add-Ins, try removing your Normal.dotm file.
It is usually located in:
Make sure there are no instances to Word running, then just delete the file,
it will be recreated when you start Word.
When you delete the Normal.dotm file you will lose any styles or customizations, everything will revert back to their default settings.
There may also be more than one copy of the Normal.dotm file floating about,
so it would be a good idea to search your system for any others.