Synchronization problems

I am backing up My Documents every Friday in a memory stick. When I want to update any file in my PC or in my dongle and copy the update in the other side, Microsoft tells me that can not be done because de file is synchronizised. I need to go dowtown to the Library with the dongle, e-mail myself the update, coming back home, open the e-mail and copy and replace the old file.

I am fed up, fed up, fed up fed up of this issue.

Can someone tell me, please, how on Earth to disable the synchronization?

With thanks in advance for your kindness.