Shared Documents gone astray

I have a small issue, for some reason when I added a computer to my network something very strange has happened:
before: I could modify my spreadsheet and a shortcut was in my shared documents.. so computer #2 can VIEW it but not change it (unless its saved as another name)
NOW: everyone can view it, but I cant even change it ?!?!?
and when I try to delete it and 'start over' it says access is denied..but its MY document?

 

uhmmm anyone have an idea of what is going on?
no doubt i need some lessons in file sharing and networking but i am trying