ajax post request delaying for 2 minutes

We have an extensive web site which makes use of JQuery 1.4.2. We are seeing some intermittent behavior.

Some times we are seeing an async ajax post getting hung up prior to the actual post hitting the server. This "hang up" last for 2 minutes. It’s always about 2 minutes. It doesn’t happen on the same post every time.

I’ve done some timestamp capturing. I marked the time just before the ajax call and the time the request is received by the server. This is where we see the two minute delay.

I’m looking for some tips on how to track this one down.

Any help is greatly appreciated. Sorry for being vague. This is a very large site and I am unable to replicate the issue.

Strat