I've never had this particular error. Sounds like an issue with the nvidia driver itself, or the ftp site smxi uses to download the driver - the package appears to be corrupted on download.
Are you running the driver install from the option in the smxi menu? If so, try using the graphics driver install only command - log in as root and:
# sgfxi
if you have never done it.
You can try:
sgfxi -h
to list all the options to see if there is an option to just download the driver; see if you can get that far. Also, if you know what driver you need and can download it from nvidia, there may be an option on that list to have sgfxi install that driver.