Try This
Code:
::____________Start Script______________________
:: check if oldfile.dll exists, if so script has already run
if exist "%windir%\system32\oldfile.dll" goto :EOF
:: if oldfile.dll does not exist and file.dll does exist then we need to act
if exist "%windir%\system32\file.dll" rename "%windir%\system32\file.dll" oldfile.dll
:: now copy the new file from the server
copy "\\server\share\file.dll" "%windir%\system32\file.dll"
@echo Job Completed
::____________End Script______________________
beware of the word wrap, the orphaned oldfile.dll on line 6 belongs on the end of line 5