I've been looking for the answer to this on @CallofDutyElite and also emailed Activision Customer Support. No response as yet. Some Beta test that was.

Yes, I was getting this everytime for a couple of days and it was becoming very annoying!

Then I read a thread in this forum and did what was said and it worked!!

Basically, whne you get that message, keep pressing tab. Now, I'm not sure what the technical terms are, but, you're tabbing through all the 'clickable' sections on the page; Keep doing that about 20-30 odd times (slowly) and eventually you're get to the original text box where you typed your chosen clan name and got that message. Type the clan name again and you're away....

Probably a page coding error, or something