I creat he.net ipv6 tunnel and I using windows 2003 IIS6 working ipv4 the same server. I have install wordpress blog in the windows server. but the wordpress always Could not resolve any host domain. only when i use ipv4 network that is normal work.

who can help me, How I do fix it ? 

yes. when I disconnect ipv6 network, wordpress is normal.  I have see many posts about Could not resolve host in wordpress.org forum. However, without solving the problem.

I use the windows 2003 system IE browser to visit other sites seems normal, but slowly resolve domain names.

He did not solve the problem resolving the domain name.   you may find about many posts in http://wordpress.org/search/Could+not+resolve+host?forums=1