Hi all, Seems my 503 issue is occuring on vbulletin forums with medium to high traffic. This is the original thread: http://www.litespeedtech.com/support/forum/showthread.php?t=3801 However, it now is occuring on another server with a busy vbulletin forum and the logs show it only happens to Firefox users as well. I've had 3 different server companies review the issue and paid Litespeed support as well to no avail. I agree with Litespeed it is likely not a LSWS issue but rather some obsure PHP issue. I'm just hoping someone might have some more suggestions. I quick google search shows other vbulletin forum owners running litespeed with the same issue. Most of them report the errors only show when hitting the file showthread.php. What could be so different about that file and Firefox to throw a 503 error is the $64,000 question. Thanks in advance.