Rob,
I had a similar issue a couple of week's back and found that (in my issue) it was just related to having an additional form on the page that preceded by second form so when adding client validation, it actually didn't set the form id correctly. One thing you may want to check is in your Behaviors Panel (Not Server Behaviors) and look at the Client Validations... first make sure they are all there and then inspect them... I had to manually change the form to reflect the correct form id to fix the issue. I think Ray said in future versions, this would get fixed as the Client Validation would then assign form ID names if one did not exist as the problem I had seemed to be related to the fact that validation currently assigns an array such as form(0), form(1), etc.
Best regards,
Brian
