Cannot access my site or control panel. Cannot find server. DNS error.

I cannot access my site or my site control panel. I get a
cannot find server dns error. I checked with the host and
the site is fine from their end. I've run virus scan and
spyware scan and found nothing. I've checked my browser
settings too. Ping returns "cannot find host". I can
access other sites fine. I've tried refreshing and
rebooting, but nothing works.

I'm using XP SP1 with wireless modem. RoadRunner is my
ISP.

Any suggestions? Thanks.