Error message during installation

During the installation process (either via the upload method or installation using the tmp directory) I get the following error:

HTTP Error 500.0 - Internal Server Error
The page cannot be displayed because an internal server error has occurred.

Most likely causes:
IIS received the request; however, an internal error occurred during the processing of the request. The root cause of this error depends on which module handles the request and what was happening in the worker process when this error occurred.
IIS was not able to access the web.config file for the Web site or application. This can occur if the NTFS permissions are set incorrectly.
IIS was not able to process configuration for the Web site or application.
The authenticated user does not have permission to use this DLL.
The request is mapped to a managed handler but the .NET Extensibility Feature is not installed.

Things you can try:
Ensure that the NTFS permissions for the web.config file are correct and allow access to the Web server's machine account.
Check the event logs to see if any additional information was logged.
Verify the permissions for the DLL.
Install the .NET Extensibility feature if the request is mapped to a managed handler.
Check the failed request tracing logs for additional information about this error. For more information, click here.

Detailed Error Information:
Module FastCgiModule
Notification ExecuteRequestHandler
Handler PHP via FastCGI
Error Code 0x00000000
Requested URL http://com-gc-office:60194/administrator/index.php?option=com_installer&view=install
Physical Path C:\Documents and Settings\gavin.colton\My Documents\My Web Sites\joomla_16\administrator\index.php
Logon Method Anonymous
Logon User Anonymous
Request Tracing Directory C:\Documents and Settings\gavin.colton\My Documents\IISExpress\TraceLogFiles\JOOMLA_16

More Information:
This error means that there was a problem while processing the request. The request was received by the Web server, but during processing a fatal error occurred, causing the 500 error.
View more information »
294807

Hi,

do you still have problems?

best regards,
Viljem

It seemed to be a problem with Joomla 1.6. I've downgraded to Joomla 1.5 and it now works.