The network interface uses SNMP to determine if the printer is ready. If you disable SNMP, the driver should assume that it's always ready, always full of paper, always not busy, etc. If your Windoze 7 64 bit box has SNMP running, but SNMP is blocked in the internel firewall, the computer can send SNMP commands to the printer, but the replies and traps will get blocked by the firewall.
The 1320cn only comes with 64MBytes of non-expandable RAM. If you try to print a large and colorful page, it will chew on it for many minutes, and then silently quit. Same problem is your "small print job" is loaded with fonts that are not resident in the printer. I'll spare you my opinion on the quality of this printer.
My guess(tm) is also firewall compatibility.