I received a response to my inquiry:
We have verified that your account has been deactivated. This could have occurred for many different reasons including but not limited to, the quality of data returned on various surveys, having more than 1 account, speeding through surveys, etc. We will look into the reason why your account was deactivated and get back to you soon.
I don't feel that I fall in to any of those categories - I do answer some of the initial prequalification questions quickly, just because I am so used to them that I know what I'm doing, and have a fast connection, but have never "sped" through a survey, nor would I have more than one account. Funny that I'm not the only one this happened to today, and while cashing out (this sounds just like the OP's issue). Does this mean you never get your account back? OO was my top earner.
BTW - just as I suspected - my SurveySpot account, which I never use anymore, was frozen also.