Win Server 2003 - Permission cannot be acquired when run ASP.Net application

[sutcliffe_grant]

I am getting the following (below) error when attempting to run a
DotNetNuke website on a Win Server 2003 machine. I do not get the
problem if running this on an XP machine.

I have set permissions in IIS to allow everyone (having already tried
other accounts i.e. Net Service account), I have tried with Windows and
anonymous ticked in the security tab for the site in IIS. I have added
the website to the Exclusion list in SharePoint Administrator. The
application is under the default application pool. I have fiddled with
the Virtual server web.config in addition to the website web.config
file. I am not sure what settings I might need to change on line 198 in
the machine confige which is 'assembly *' - indicating that all
assemblies will be peritted.

Hopefully someone can help with some pointers on what I might do.

Thanks in advance.

Error message below:

Cheers

Grant

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: Required permissions cannot be acquired.

Source Error:
[No relevant source lines]
Source File: machine.config Line: 198
--------------------------------------------------------------------------------
Version Information: Microsoft .NET Framework Version:1.1.4322.985;
ASP.NET Version:1.1.4322.968