[Cryo]

Well, I'm assuming you're going to need to re-upload everything to your Linux site and change some settings (possibly FTP settings, etc.). You may have to wait until tomorrow to see if they can't just copy everything over. It definitely seems like the bad host is related to a DNS issue and that problem will fix itself over the next day or so. The files are another issue though because again the Linux server and IIS are two different machines. I'm glad we at least found out that IIS was the root of your issue, and in the long run it's probably better that you switched it to Linux hosting anyway for this particular application.

You could also try switching it back to IIS again and see if the site comes back. If it does my conclusion about the IP / server changes is most likely right. Check the email that your account is registered to, there may be more instructions for the Linux change.