“Some” WP sites hang on my server

Hope I posted in the right place. Couldn’t find anything in the search related to my issue.

*Note*: Apache and MySQL has been rebuilt, no vulnerabilities on these sites, no incomming or outgoing attacks, mod_security rules have been checked and some comment spam rules added, and no errors for this found in any server logs. My Data Center has been stumped for more than two weeks because they cannot see any logical reason why only these sites have this intermittent hang issue. Database fixes were ran for all sites affected. Sometimes restarting Apache will help, other times it will not.

I have a ton of clients running WordPress on my server, but there’s only about 5 or 6 sites on my server running WP that have intermittent hangs. Sometimes the page will only load halfway (like the footer won’t load and only half of the sidebar), and sometimes the page won’t load at all. Some of these sites are running WP 1.5.2 and some of these sites are running WP 2.0. Not all of these sites are using the same themes.

Here’s the odd thing… once able to get into the admin panel, everything loads fast and there are no hangs. But if you open the site (not the admin panel) in another tab window it hangs. How can it hang on the outside and not in the admin panel?

The other odd thing (I’ll give you an example of my personal site, can’t give one for clients). If I go to http://subliminalconfusion.net this is where the hangs occur. But if at the same time I open another browser tab and go to my test site http://subliminalconfusion.net/wordpress I get no hangs at all. At one point I completely removed all of the plugins, which made no difference. I also turned off trackbacks and pings, and removed the one ping address in there.

Can someone tell me if this might be an RSS issue of some type, or if it might be something else?

Thank you in advance for your patience and replies.