Firewall-antivirus conflict

Help! I seem to have a software conflict. I was running ZoneAlarm with Norton Antivirus 2001. Then I d/l NAV 2003 and with both it and ZA running, my PC (running Windows ME) kept locking up, so I uninstalled NAV.

Next I uninstalled ZA and reinstalled NAV, then d/l and installed Kerio Personal Firewall. Same problem - PC kept freezing up. I disabled Kerio and everything was fine, so I uninstalled it.

I d/l Tiny Personal Firewall and tried to install it, but it doesn't support Windows ME.

So now, I'm without a firewall and VERY uncomfortable with this situation.

Do I try to find another anti-virus program (money is a slight issue right now) and reload ZA or Kerio, or is there a firewall out there that won't conflict with NAV?

By the way, I have run Scandisk and Defrag, as well as Spybot, throughout all of this.

Thanks in advance for any and all advice...