There's a few of us who are having this problem. There are at least 2 previous forum threads discussing this, so there must be something wrong there. Would you please report this to O2 Customer Services, and mention these forums and that you're not the only one with the problem.
In a nutshell, the free text webpage seems to be sending the browser in an endless redirect loop, which is causing it to 'crash' and not show the page.
This happens with Internet Explorer, Firefox, Chrome and Safari in both my home and workplace. I assume it's happening with all your browsers too?