protect cells only after information is entered
 

I need to create a spreadsheet that will be housed on a server. Multiple
users will access the sheet to enter information. Is there a way that a cell
can be locked or protected after information is entered? I don't want anyone
(Including the user entering the information) to be able to change the
information once it is entered.
Ideally the protection would occur once the entire row of data is entered,
but if it can only be done on a cell by cell basis that will work too.