With WAMP 2.2 serving Apache 2.2.21, MySQL 5.5.16 and PHP 5.3.8 on my Windows XP development machine, I can connect and manage my database via phpMyAdmin or any locally hosted PHP script using a DNS like "mysql:host=localhost;dbname=kwamjing"
When I try to connect to MySQL via a management tool like HeidiSQL or MySQL Query Browser I get
Error 2003 Can't connect to MySQL server on 'localhost' (10061)
Can a firewall block HeidiSQL from accessing 127.0.0.1:3306 but not PHP?
UPDATE:
Looking at my active connections through netstat -an I see only the ipv6 loopback listening on 3306
Active Connections
Proto Local Address Foreign Address State
TCP 0.0.0.0:135 0.0.0.0:0 LISTENING
TCP 0.0.0.0:445 0.0.0.0:0 LISTENING
TCP 0.0.0.0:2869 0.0.0.0:0 LISTENING
TCP 127.0.0.1:80 0.0.0.0:0 LISTENING
TCP 127.0.0.1:1025 0.0.0.0:0 LISTENING
TCP 127.0.0.1:2215 127.0.0.1:2216 ESTABLISHED
TCP 127.0.0.1:2216 127.0.0.1:2215 ESTABLISHED
TCP 127.0.0.1:2217 127.0.0.1:2218 ESTABLISHED
TCP 127.0.0.1:2218 127.0.0.1:2217 ESTABLISHED
TCP 127.0.0.1:5152 0.0.0.0:0 LISTENING
TCP 192.168.0.103:139 0.0.0.0:0 LISTENING
TCP 192.168.0.103:2869 192.168.0.1:4530 CLOSE_WAIT
TCP 192.168.0.103:2869 192.168.0.1:4532 CLOSE_WAIT
TCP [::]:135 [::]:0 LISTENING 0
TCP [::]:2869 [::]:0 LISTENING 0
TCP [::]:3306 [::]:0 LISTENING 0