You could disable smart screen but you may not want to do that.
So you were originally running 1.6, reinstalling battlefield 1942 should put you back to version 1.6.
If that doesn't work I could up load the 1.6 versions of the files that were updated in the 1.61 patch and you could replace them yourself.
Im going to reinstall it after we get our own Server. But go ahead and put those patches up now, just in case if I need them.