Submit news reacts differently to each browser

[SpudULike]

Hi. I'm running CMS Made Simple 1.10.3. I'm using PHP 5.3.8, and MySQL 5.5.16. This is all working with Apache 2.2.21 running on Windows 7 32bit (test environment)

I'm using News v2.12.3, and FrontEndUsers v1.17 with CGExtensions v1.27.9 and CustomContent v1.7.3. (not sure which may be causing my issue, so gave them all)

When I try to sumbit a news item from the frontend without logging in I get the expected error message that goes with the 'restricted' code placed in the template, but when I login with a user who has FEU rights to post news items I get different errors depending on which browser I'm using.

If I use IE9, whilst logged in to my site I can get the news form, but when I hit the 'submit' button nothing happens, literally no refresh, no items added in the background, nothing.
If I use Firefox 11, I can't click on the 'submit news' link at all. It's like the link doesn't exist.
If I use Google Chrome, with the same user, I can sumbit a news item no problem.

Hopefully I've given you all enough information, but if not, please let me know and I'll post extra here if I can.

Thanks for your assistance