Excel Viewer causes problems saving shared spreadsheet
 

My company uses a spreadsheet for it's production schedule. The spreadsheet
is in a shared folder on a server. Permissions allow only members of the
group 'production' to make changes. Everyone can open in 'read-only' mode.
The spreadsheet is saved with the Save Option "Read-only recommended"
checked. Everything worked fine until we tried to expand the availability of
the schedule to shop-floor workstations that do not have Excel installed. We
downloaded the Excel Viewer on those workstations and were able to open the
production schedule spreadsheet. We then noticed that an authorized user
making changes to the schedule was unable to save his changes if the
spreadsheet was also open on one or more of the workstations that use the
viewer. After a considerable delay, they received an error message: "Your
changes could not be saved to 'PRODUCTION SCHEDULE.xls, but were saved to a
temporary document named '6398BB40'. Close the existing document, then open
the temporary document and save it under a new name."
Is there a way to overcome this problem?