(NT AUTHORITY\NETWORK SERVICE) does not have write access -- same problem again

I encounted the "The current identity (NT AUTHORITY\NETWORK SERVICE) does not have write access to 'C:\WINNT\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files'." error again, and this time I have to give access right to the user "NETWORK SERVICE". And the funny thing is that I DID NOT KNOW there's a user called "NETWORK SERVICE" before. Oh well, better late than never.