Events error in form...but what is it??

Hi,

i've just tried to edit an event on my site (just the time and date) and it's now telling me that there's an error in the form and won't update.

now, there might be an error in the form, but I can't see where it might be and just saying there's an error but not saying what it is...even highlighting the field where the error is would be immensely helpful!!

I think it may well be in event creation too, as I've just received a message from a member saying a similar thing.

Many thanks
Paul