rtf files causing Microsoft Word to freeze

I have some rtf files that were saved to my computer from the internet and they will open fine in text edit, except the header doesn't show up. I open them in microsoft word and after the window opens I get the spinning beach ball and word freezes. This is the case for most of them, but one of them opened fine. I viewed the info for both rtf files and they seemed to be identical except for the file size. Any ideas on what would cause this type of behavior?