Sean - I assume you are talking about the 4.5 update. Some significant changes in this release.
No problems getting it installed for 4.5 or any of the previous updates. Maybe your download was bad for some reason. Try, try again!
Poke around on
http://forum.naviter.com to see if others are having issues and/or post a message.
Let us know what you find. Good luck.
- John