IE - Forums plugin is not resolving after 'send' post in thread

We have installed the forums plugin on a page on our site.
This simple plugin is great its all we need BUT
When posting a response on IE - yes I know I dont use it neither does my partner BUT according to analytics over 50% of our visitors do hence the check - the plugin and therefore the site gets stuck at this URL:
And the header is rendered but no the page.
when you reload the forum page the post IS there and if I do the same thing on firefox and Chrome all is good - no problems - this needs to go live tomorrow - any chance anyone could help?
Much appreciated