You've done the basics. Check for new or updated drivers for your wireless hardware. Remove and re-install your current driver if you haven't already.
Even considering there are no other wireless networks in range, try changing the wireless channel to 1,6 or 11 and remove the profile for your current wireless connection.
Change or re-enter your wireless encryption passphrase.Re-establish the connection as if you were setting it up for the first time. Disable ZoneAlarm while troubleshooting.