radius.log test?

Hi all, I have suddenly started seeing this in the radius.log ( 2.2) Mon Jul 18 11:36:23 2011 : Auth: Login incorrect: [TEST/<+\253\362\023\213\223-~\272\257]$\003\033\211] (from client localhost port 0) All seems well besides this. It started happening a day ago every 30 seconds. Anyone understand what this is? Regards Carl