How can I get Excel 2007 to its default "factory setting"
 

Is it possible to get Excel 2007 to it's what is called "factory settings".
I accidentally downloaded an add in that has altered some of the excel
settings that I can not reverse back. The add-in errors do no appear when
some other user name is used in the network. I tried to reinstall Excel, I
uninstalled it and reinstalled it back, but the problem does not go away.