Fix comment script that doesn't work in IE 8 & 9 (works in all other browsers)

Avg Bid (USD)
Project Budget (USD)
$30 - $250

Project Description:
Hi, I've got a comment script which is working fine in all browsers apart from Internet Explorer (version 9 and below).
You can check it out and test here -

Basically if you add a comment it sends it through and seems to be working fine but then if you refresh the page it disappears.
Also if you click on the thumbs up/down for a comment this also seems to work fine but again, if you refresh the page it disappears.
The comments are going through and being saved though. If you check on another browser or restart IE the comment will appear, as well as whichever thumbs up/down arrow you press.
If you add a comment in another browser like firefox/chrome and try refreshing the page the page in IE it won't show the comment. Only if you restart the browser.
It works totally fine in the other browsers (even IE10) and also strangely it works fine in IE when in my local host. It might be a cookie issue (session?) but I'm not sure.

It might be a simple issue. If you think you can fix let me know!
(I would upload the script but i bought it a while ago and isn't mine to show.)
The script has a few seperate folders and pages but i think the issues can be narrowed to only a couple of these pages.

Skills required:
AJAX, jQuery / Prototype, MySQL, PHP, Software Testing
Hire rocon4
Project posted by:
rocon4 United Kingdom
Public Clarification Board
Bids are hidden by the project creator. Log in as the employer to view bids or to bid on this project.
You will not be able to bid on this project if you are not qualified in one of the job categories. To see your qualifications click here.

$ 99
in 2 days
$ 103
in 2 days
$ 123
in 3 days
$ 128
in 1 days
$ 123
in 1 days
Hire afcn007
$ 45
in 0 days
$ 50
in 2 days
$ 35
in 1 days
$ 44
in 3 days
$ 55
in 1 days