This could be related to the new HTML5 parser in Firefox 4. It is a bit stricter about a site's coding than the parser in Firefox 3.6. You can test by turning the parser off.

(1) In a new tab, type or paste about:config in the address bar and press Enter. Click the button promising to be careful.

(2) In the filter box, type or paste html5 and pause while the list is filtered

(3) Double-click html5.parser.enable to toggle it to false (it will turn bold).

Then reload the problem page (or your cart) and test again. Does that make any difference?

Hi I'm afraid it didn't make any difference. I tried restarting the computer with this change but that did not help either. Any other suggestions?

Just one other guess: Firefox allows sites to post data from their own form to a payment processor's web server, but if you use the NoScript add-on, it could be blocked in there. If you use NoScript, see whether it posted any messages in the Error Console. For best results, open the console (Tools menu > Error Console) and click the Clear button first, then try the action that doesn't work correctly and check for new errors or messages.

Incidentally, when I try that domain, I am redirected to a .co.uk domain. Same for you?

Hello I am trying to buy another ticket from first great western but still getting the same problem. Thanks for your previous reply. My first question (and I'm sorry but quite a stupid one) where is the tools menu? I click on the firefox drop down but can't see it there

Ignore the above I have found the error console Firefox>Web Developer>

I get the following errors www.buytickets.firstgreatwestern.co.uk : server does not support RFC 5746, see CVE-2009-3555 secure.barclaycard.co.uk : server does not support RFC 5746, see CVE-2009-3555 secure.barclaycard.co.uk : server does not support RFC 5746, see CVE-2009-3555

I think those warnings relate to the strength of the secure connection between Firefox and the server. But those don't explain why features on the page would be broken. If those are the only messages in the console, I'm not sure I can help further. Have you reported it to the site's webmaster (assuming they have a feedback form)?

One other thing to try is to test with a clean Firefox profile. This will bypass all customizations.

First, I recommend backing up your Firefox settings in case something goes wrong. See Backing up your information. (You can copy your entire Firefox profile folder somewhere outside of the Mozilla folder.)

Next, close Firefox 4 (or 5) and fire up the profile manager as described in this article: Managing profiles.

If that works, there could be a conflict between the site's code and one of your add-ons or settings.

This issue can be caused by corrupted or blocked cookies.

Clear the cache and the cookies from sites that cause problems.

"Clear the Cache":

• Tools > Options > Advanced > Network > Offline Storage (Cache): "Clear Now"

"Remove Cookies" from sites causing problems:

• Tools > Options > Privacy > Cookies: "Show Cookies"

Also check the cookies exceptions to make sure that you do not block cookies.

See also:

• http://kb.mozillazine.org/Cookies
• https://support.mozilla.com/kb/Troubleshooting+extensions+and+themes