SP-2 Hang Ups

Installed SP-2 from Windows issue of CD. I was getting
lockups which you helped me correct at the start.
Disabled windows Firewall (I use Blackice) all went well
for a couple of weeks now getting lockups again. No error
message system just stops. Checked disabled firewall on
startup, does not go to "Not Monitored Status on
startup", takes a couple of minutes it will then drop in
if it has not locked up. Checking in control panel shows
that Windows in monitoring McAfee as the Virus program.
Becoming quite frustrating would appreciate any help.
Fridgeman