Huge embarrassment for ourselves and we are very very sorry for the messing around.
Basically, the new site was up for around 6 hours and for - as yet - unknown reason was highly unstable. We've taken the decision to revert to the old version of the site while we fix it. We're hoping this will take no more than 48 hours. Another knock-on of this is that we need to take the whole site down shortly (probably tomorrow) for around 2 hours!
For all those of you who registered on the new site, you're registrations will be safe.
Once again we're very sorry and very embarrassed!