Changed permalink, website shows in firefox not in IE

Hi

I thought i would change my permalink for seo reasons(knew I shouldn’t have!) from in my custom setting year,cats,postname to postname by selecting the button in the lastest ver. of wordpress.

I then added a code generated by Yoasts code generator http://yoast.com/change-wordpress-permalink-structure into the htaccess file.

It worked for a while now my website shows in Firefox and doesn’t show in IE.

Does anyone have any tips on sorting this out, any help would be most appreciated.

Thanks