installation as service failed on windows xp

Hi,

The first time I install postgresql in Windows XP, I install it as
service. The installer asked me to create postgres account. Ok, fine...
then someday I uninstalled postgresql so I can install the newer version
of postgresql. But first to make it clean, I delete the postgres account
from right clicking the My Computer, then click the properties. Choose
the advanced tab, then click the user profiles setting buttons.

Then when I try to install as service with postgres account, it said :
Invalid user name specified: Logon failure: unknown user name or bad
password.

I try to create postgres account from start menu ---> account or control
panel --> user account, it said that The account already exists. But
there is no postgres account in User Accounts window.

So the questions is:
1. How do I really delete the postgres account that created by
postgresql installer???

Thank you.

Regards,

Akbar