If I execute:

[c:\]sn -k a.sk

Microsoft (R) .NET Framework Strong Name Utility  Version 1.1.4322.573
Copyright (C) Microsoft Corporation 1998-2002. All rights reserved.

Failed to generate a strong name key pair -- Access is denied.

I'm the local admin. I checked with FileMon
[http://www.sysinternals.com/ntw2k/source/filemon.shtml] and access is
denied error happened when accessing the folder

C:\Documents and Settings\<user>Application
Data\Microsoft\Crypto\RSA\S-1-5-21-35927030-470637511-1426223253-1408

I renamed 'Crypto' to 'CryptoX' and it worked, but then ASP.NET stopped
working. I repaired my Windows XP installation, ASP.NET is working again but
I still get the Access is denied error.

BTW, I'm the local administrator, I've tried to manually add/delete/update
files to that folder and I was able to do it.

Any ideas?

Thanks.