installation bug-cannot create user name

Hi,

I tried downloading this product because it is required in order for me
to use another program I paid for, pokertracker.   Yet whenever I try
installing postgreSQL it brings up an error message that last part of
the install saying "could not create user name"   and then some other
stuff about how this may affect post-install operations.  Anyone know
what I can do to get this program on my computer??


Thanks,

Tate Smith