WP does not automatically prompt for updates, Akismet can never connect

Hi all,

Currently I have two WP blogs running under the same host, one under each subdomain. For example, wp1.myblog.com and wp2.myblog.com

wp1.myblog.com works perfectly, not a problem at all.
wp2.myblog.com on the other hand, does not automatically check for new updates. Plug-ins that require to connect to external server, such as Akismet also fails to connect and keeps on returning unable to reach any Akismet servers. Apart from the above, everything else also works as it is, including uploading images/videos, making post/pages and correctly running of all plug-ins (except Akismet).

It feels like wp2.myblog.com is trapped behind an invisible firewall which it is unable to break free. But wp1.myblog.com works without a glitch.

Both wp1 and wp2 is set up the exact same way. Each uses its own SQL DB, and has its own separate installation of WordPress 3.1.

It should not be a problem with my host or php configuration otherwise both wp1 and wp2 should suffer the same problem. Therefore I have nailed it down WordPress configuration.

I checked WP configuration to ensure both wp1 and wp2 are the same, I even used the same .htaccess from wp1 in wp2, but problem just remains at wp2.

Updating to the latest WP does not help (I haven’t tried 3.1.1 but this problem has remained since 3.0). Updating to the latest Akismet also does not help.

Can someone enlighten me here? I am really out of ideas.