need help asap pleasee

got 4 private messages form a guy saying

alert(document.cookie)

he used the vb points sytem and he donated one point each time with that mesage

wel after that i noticed he was in the vb store so i banned him, banned his ip addres, and banned his ip addres from my server.

but know when i clicked the vb store button i get a pop up that says

the error i get says idstack= and a bucnh of numbers and also says bblastvisit=
and alot of number

it also says userd id= a bunch of numbers and user id and abunch of number=

i changed my pass and every time i go to the store i get this message now but i need help to know whats going on