Over the past day there has been issues with our installation of PHP. We have made good progress but are working to iron out more problems and would appreciate your patience. Sorry for any inconvenience caused.
UPDATE (21 May 2009, 18:40 BST):
Remaining issues should be resolved within 24 hours.
RESOLVED (22 May 2009, 19:20 BST):
We have now completed tests which we believe show we have resolved every outstanding issue. If you come across something which you believe we have missed, please contact technical support. We have also used this opportunity to add some enhancements and security updates.