ver 7.2.2

Hi Friends

I have an ancient database whih has about 7 sessions in there which aren't user sessions.
They have sids and serial#'s as follows :

sid serial#
1 1
2 1
3 1
4 1
5 1
6 1
7 1

when I try an kill any of these sessions I get an error explaining that they are not user sessions

Does anyone know what type of sessions they could be ?

Thanks

Suresh