The file is too large. I'd suggest ftp-ing the file to your server and asking your host if they can import it for you. You'll have to comment out the lines in the install.php file that relate to importing the ZipData database. Don't touch the line that creates the database, just the part that imports the data.
As far as any errors on the zipcode thing please post them as the thread your trailing on is old and already fixed so since this has been tried on many installs with success I would be interested in knowing your issue.
The zipcode installation took a whole 3 seconds to import the 70604 inserts when I installed classifieds provided the memory override was in place as I posted above.
Ok, the prefix fix imported two of the 7 usergroups, but it works enough to get admin going, thanks.
I do not find any PHP or HTTP errors, but I did get the blank screen. When I get time, I will try it again as a fresh install. I tried it three times and it did not work, but will do again. No dbout I am doing something stupid.