I am seeing similar issue. I found the 'clue' mikekist mentioned above, in fact found that as an alternative, if you have the ability to login to your server remotely, you can browse to the url in you30's post via a browser on that computer and see the actual errors as suggested in mikekist's post.
I've done that and my issue is surely with web.config as the errors suggest:
Server Error in '/' Application.
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Configuration Error
Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately.
Parser Error Message: It is an error to use a section registered as allowDefinition='MachineToApplication' beyond application level. This error can be caused by a virtual directory not being configured as an application in IIS.
Source Error:
Line 57: </system.codedom>
Line 58: <system.web>
Line 59: <machineKey
Line 60: validationKey="40-alpha/numeric-characters"
Line 61: decryptionKey="Same40-alpha/numeric-characters+additional-5-characters"
Source File: C:\Inetpub\vhosts\mydomain.com\httpdocs\web\web.config Line: 59
Show Additional Configuration Errors:
It is an error to use a section registered as allowDefinition='MachineToApplication' beyond application level. This error can be caused by a virtual directory not being configured as an application in IIS. (C:\Inetpub\vhosts\mydomain.com\httpdocs\web\web.config line 106)
It is an error to use a section registered as allowDefinition='MachineToApplication' beyond application level. This error can be caused by a virtual directory not being configured as an application in IIS. (C:\Inetpub\vhosts\mydomain.com\httpdocs\web\web.config line 167)
It is an error to use a section registered as allowDefinition='MachineToApplication' beyond application level. This error can be caused by a virtual directory not being configured as an application in IIS. (C:\Inetpub\vhosts\mydomain.com\httpdocs\web\web.config line 175)
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Version Information: Microsoft .NET Framework Version:2.0.50727.42; ASP.NET Version:2.0.50727.42
==================end of errors
I've looked at IIS, not sure what to do with the virtual directory as suggested in the error doc. I have DNN 3.x installed in some other domains on my dedicated server, but gotta get by this issue with 4.x. Running Windows 2003, SQL Express 2005, Asp.Net 2.0.
Clues to pass on? Much appreciation for fixes.
jsunder