nginx/0.8.54 502 bad gateway,very strange

[zhuokun]

hi, guys.
    I have a big problem, it torture me two days.
    centos 4.7, nginx 0.8.54, php  5.2.14.
    There's a page, it's has four frames each include a php file.
    502 bad gateway occured when I use chrome open it. 
    But seldom happened when I use IE.
    because IE load four php filese sequenced, but chrome paralleled
load the four php files.
    I test a single php file with LoadRunner, no 502 happened.
    
    It's confused me.
    thanks a lot.

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,213624,213624#msg-213624