Unable to browse the SharePoint site Event ID: 1000

I had worked on a recent support issue where user when tries to browse the MOSS site it prompts for authentication multiple times and finally gives a message "You are not authorized to view this page"

Errors in the application event viewer
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Event Type: Error
Event Source: .NET Runtime 2.0 Error Reporting
Event Category: None
Event ID: 1000
Date: 3/16/2009
Time: 3:01:25 PM

Faulting application w3wp.exe, version 6.0.3790.3959, stamp 45d691cc, faulting module kernel32.dll, version 5.2.3790.4062, stamp 462643a7, debug? 0, fault address 0x0000000000027d8d.

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Reinstalled .NET 2.0 -> error still occured.

We tried to attach the content DB to a new web application and still the issue occured.

Checked if the user is able to access the settings.aspx and he was able to browse.

Also was he was able to browse the subsites without any issues.

We found that the issue happens only while browsing the default.aspx of the root site collection.

We created a new default.aspx as a welcome page and was able to browse the SharePoint Site successfully.

Else if you have a backup copy of the default.aspx replace the same with the corrupted one.