Unable to Edit Shared Workbook

XL2K-Two of my customers are unable to edit a shared workbook. This workbook
is stored in a network folder where many users have been granted rights to
view teh document. The only two people that can make changes are the two that
have rights to do so but are unable to for some reason. We have checked the
folder and network rights and they both are correct yet are unable to edit
the document. What are we missing here? Would the document author ahve
anything to do with it since we all have our author defaulted to our company
name? Any suggestions would be great. Thanks.

when excel saves a file, it creates a temporary file, saves to that, deletes
the original file, then renames the temp file to the original name.
do they have rights to do all that?