This may be due to several reasons. If your site redirects to our corporate site it could be due to the DNS records not resolving correctly or that the site has been suspended. If you check ClientZone, you can ensure that there is no suspension on the domain.
If you recently upgraded the site from a Parking or Pointing package, it can take a few hours for the DNS changes (poining from our parking server to the IP address where the content resides) to resolve locally and internationally.
Check your DNS records in ClientZone to ensure that they point to the correct content server (you can run a dig, nslookup or ping to ensure that the server is valid and responding).
Otherwise drop me a mail so I can check it out for you - firstname.lastname@example.org