Hi, DjDede.
If the problem lies with localhost resolution, it may indicate that localhost is resolved as IPv6 ::1 address, instead of IPv4 127.0.0.1. UltiDev Cassini does not listed on IPv6 addresses - only on IPv4. You can verify that by pinging localhost and see how it's resolved. If you need to change localhost address, you can do that by modifying "hosts" file in "c:\WINDOWS\system32\drivers\etc" folder. However, if localhost is resolved as 127.0.0.1, then it's not a DNS issue.
Another thing keep in mind is that Cassini service is running under "Local System" user account. This user's permissions may affect how security-related code behaves in your app. When you run your application in IIS, it's likely to run in "Network Service" account context (which is more restricted than Local System), and when you debug your ASP.NET application in Visual Studio development web server (WebDev), it is running under your own user account.
Please let us know what you have found.
Best regards,
UltiDev Team.
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