Do you happen to have Outlook 2003 installed? Did a quick google search and seems to be the cause .. why I don't know.
*edit* - I have no idea if this works but from reading you can hit ctr-alt-del when you get the error message (without hitting ok) and look for setup.exe and kill that. Then you should be able to upgrade the app. Again I have no idea but you could try it.
I had retried downloading the file again but the same problem. since it is a rar file and tried to open it with winace the problem still existed. i will try to open it with winrar and repair the file, then try to install it again. thanks again.