Windows 7: Problem Applying Themepack Due To Name Of File

Hi - I'm trying to save a theme for sharing (create a themepack). However, once save the file and then try to double click on it, nothing happens (I'm trying to name it "C - Blue Christmas.themepack). The thing is if I name the file differently it works (if I leave out the spaces before and after the hyphen). I can't figure out why this would happen. I've successfully saved other theme packs with spaces before and after the hyphen (ie C - A Midnight Clear.themepack). I don't know why this one is being tempremental. I've had problems with other theme packs if I tried to put an apostrophe in the name but now I wonder if the apostrophe was the problem or if there was something else going on. Any ideas? Thanks!