The one time I did get that error was when I tried to install it the normal way and it attempted to update which failed repeatedly. May not be the case here, but if it is..then downloading https://www.dropbox.com/s/1lqmlgw9heagi5d/Realm.rar?dl=0 ...which is a winrar'd copy of my Realm folder and then copying the folder over the old one overwriting all the files (or putting this 1 in its own folder and running wlaunch) should fix it.
Just a note that you'll have to set the compatibility properties on sciw.exe and wlaunch.exe again. That is to say (depending on windows version) ... xp sp3 compatibility, disable visual themes, desktop composition. You can also set it to run as administrator but I haven't noticed if that one really makes a difference.