Resetting fax answer rings

I am running XP on a 1-year old Gateway and using an HP
570 OfficeJet that is about 6 years old. Everything has
been running fine but about 2-3 weeks ago, the answer
rings automatically go from 6 (which is the correct
setting for use with an answering machine) to 1 if the
computer "goes to sleep" while I am online, if I sign off
my ISP and let it go to sleep or after a second call
comes in when I've been online. I can't figure out why
it keeps resetting. I'm having to turn my fax off when I
am not at home so that the answering machine will pick up
instead of the fax. I am on AOL broadband. I don't
think it is the HP unit...I'm thinking some recent XP
upgrade may have done it. I've done everything but
reinstall the printer/fax as process is a little
complicated because the old HP really doesn't like
talking to XP...but am willing to do it if only option.
Thanks.