Actually after looking at that file its size is very small at around 200 mb. The full installer is closer to 300 mb.
Try downloading this file first, then run the file from the updtae site against this install.
http://www.bobcadsupport.com/tech
Click the link that says
"Bobcad software installs" and choose V23. Download and install the release version first, then run the update we were just talking about against that.
Post back,
Burr