Sometimes when you try to run any application you get 'MSVCR71.dll was not found' error, recently I installed the Discoverer client and facing this issue.
It simly means that MSVCR71.dll is missing in your system. Downlaod the file MSVCR71.dll, generally it will be a zip file. extract the zip file the copy the msvcr71.dll file to the directory 'C:\Windows\System32'.
Try again, even now if it doesnt work, copy the same file to the directory 'C:\Windows\SysWOW64' and hopefully it should work now.