network leak ?

[Rivas]

i was just connected few days to the intertet and now when i restarted computer i find out i got added 1 more account to my computer in win xp pro called "blah".I'm the only one who is using computer and nobody could create from inside.I deleted that account and i also disabled: files sharing,ipx,spx,netbios,nwlink netbios.
i know its possible get into computer using nbtstat and so on if there is some inproperly configured network but i have no idea what i did wrong.
any suggestions ?

[Croc]

Have you scanned for trojan/backdoor activity?

Croc.

[Rivas]

yup no trojan
i guess if i got trojan no one is gonna bother with creating next axx to windows.