hey after a bit of messing around i found out how to do it.
go to the credential manager and then to the windows credential section. under the tab windows credentials hit add new credential. for the network addess go to thew properties of the folder you want to share then go to the sharing tab and copy the network path and past that in the address section. then for the password and username you can enter whatever you want. i like to use admin for the user name and then whatever password. click save and it should work
EDIT: incase it wasnt clear you are adding the credentials in the PC that has the drive or file you want to share. then using them on the PC you want to acces the file from.
hope that helps even though this post was a year ago.
thanks
andrew.