Vista - Remote Desktop won't run

When I attempt to start "remote desktop", I get the following error message
"The system cannot find the file
specified.......C:\.......\<LANG_NAME>\mstsc mui"
The file is in System32, and is version 6
Another file is in another folder, which is an earlier version, and it does
run.
Both files are MSTSC.EXE
Version 5.? loads fine, when I click on it
Version 6.? displays the above error message
Windows (XP) disc won't re-install the product, as it sees it as already in
the system.

I haven't had to use remote desktop before, but now, I need to.....H E L P....
thaks;
--
The French Canadian